Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback ...Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.展开更多
In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through ...In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10°was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback(DFB)grating,substrate emission with a radiation power above 1 W at 25℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of -0.2 cm^(-1)/K.展开更多
Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback （DFB） lasers using varied ridge width with a 4 x 1-multimode-interference （MMI） optical combiner and a semiconductor optical amplifier...Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback （DFB） lasers using varied ridge width with a 4 x 1-multimode-interference （MMI） optical combiner and a semiconductor optical amplifier （SOA） is demon- strated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio （SMSR） exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.展开更多
A three-dimensional electrical-thermal coupling model based on the finite element method is applied to study thermal properties of implant-defined vertical cavity surface emitting laser （VCSEL） arrays. Several param...A three-dimensional electrical-thermal coupling model based on the finite element method is applied to study thermal properties of implant-defined vertical cavity surface emitting laser （VCSEL） arrays. Several parameters including inter-element spacing, scales, injected current density and substrate temperature are considered. The actual temperatures obtained through experiment are in excellent agreement with the calculated results, which proves the accuracy of the model. Due to the serious thermal problem, it is essential to design arrays of low self-heating. The analysis can provide a foundation for designing VCSEL arrays in the future.展开更多
According to our engineering research on satellite-borne laser retroreflector array, some suggestions are proposed on how to manufacture a new Apollo LLRA that can make us measure one illuminating point and unillumina...According to our engineering research on satellite-borne laser retroreflector array, some suggestions are proposed on how to manufacture a new Apollo LLRA that can make us measure one illuminating point and unilluminating area on the moon's surface. These suggestions are: to control the dihedral angle offset within ± 0.1″; to use the larger aperture of the transparent face of cube corner prisms; to investigate how to separate out Apollo's reflected laser from mixed beam hitting on the LLR system.展开更多
The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s f...The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.展开更多
The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. T...The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array.展开更多
Far-field properties dependent on array scale, separation, element width and emitted wavelength are system atically analyzed theoretically and experimentally. An array model based on the finite-difference method is es...Far-field properties dependent on array scale, separation, element width and emitted wavelength are system atically analyzed theoretically and experimentally. An array model based on the finite-difference method is established to simulate the far-field profile of the coherent arrays. Some important conclusions are obtained. To achieve a higher quality beam, it is necessary to decrease separation between elements, or to increase the element width. Higher brightness can be achieved in the array with larger scale. Emitted wavelength also has an influence on the far-field profile. These analyses can be extended to the future design of coherent vertical cavity surface emitting laser arrays.展开更多
In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric tur...In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric turbulence. A prototype of the proposed structure is fabricated and a 2.5 Mbit/s on-off keying(OOK) modulated demonstration link over 40 m free space is built. This asymmetric array structure can effectively collect optical signal while rotating in a window angle of ±17°, and the bit error ratio(BER) keeps zero.展开更多
Thermal characteristics of multiple laser stripes integrated into one chip is investigated theoretically in this paper. The temperature pattern of the laser diode mini-array packaged in a TO-can is analyzed and optimi...Thermal characteristics of multiple laser stripes integrated into one chip is investigated theoretically in this paper. The temperature pattern of the laser diode mini-array packaged in a TO-can is analyzed and optimized to achieve a uniform temperature distribution among the laser stripes and along the cavity direction. The temperature among the laser stripes varies by more than 5 K if the stripes are equally arranged, and can be reduced to less than 0.4 K if proper arrangement is designed. For conventional submount structure, the temperature variation along the cavity direction is as high as 7 K, while for an optimized trapezoid submount structure, the temperature varies only within 0.5 K.展开更多
A diode laser array(DLA)positioned in an external cavity can receive the radiations emitted from its neighboring elements (C 1) and that of itself (S) after being reflected at the DLA facet as well as from the externa...A diode laser array(DLA)positioned in an external cavity can receive the radiations emitted from its neighboring elements (C 1) and that of itself (S) after being reflected at the DLA facet as well as from the external mirror (C 0). Considering the fact that｜C 0/S｜ should be larger than unity if the external cavity is effective,and｜C 1/S｜ should be larger than unity if the phase locking may be established in the external cavity.The requirements on the reflection at the facet of the diode laser array have been specified in terms of the cavity length and reflection coefficient of the external mirror.展开更多
We report one thick layer of hard-baked photoresist mask.The laser array stripe pattern was defined by standard wet lithography.With this mask, a 10 W QCW(quasi-continuous wave) operation of a narrow proton implanted ...We report one thick layer of hard-baked photoresist mask.The laser array stripe pattern was defined by standard wet lithography.With this mask, a 10 W QCW(quasi-continuous wave) operation of a narrow proton implanted multiple stripe conventional single quantum well separate confinement heterostructure(SQW-SCH) GaAlAs diode laser array has been realized.These devices exhibit the lateral far-field radiation pattern of a phase-locked array of gain-guided semiconductor injection laser array.The twenty stripe laser array has a lateral far-field beam divergence full width at half maximum(FWHM) of less than 3°,and three twenty stripe laser array has a beam divergence in the plane of the junction of about 9°.展开更多
An external cavity quantum cascade laser （QCL） array with a wide tuning range and high output power is pre- sented. The coherent QCL array combined with a diffraction grating and gold mirror is tuned in the Littrow ...An external cavity quantum cascade laser （QCL） array with a wide tuning range and high output power is pre- sented. The coherent QCL array combined with a diffraction grating and gold mirror is tuned in the Littrow configuration. Taking advantage of the single-lobed fundamental supermode far-field pattern, the tuning capa- bility of 30.6cm-1 is achieved with a fixed injected current of 3.5 A at room temperature. Single-mode emission can be observed in the entire process. The maximum single-mode output power of the external cavity setup is as high as 25mW and is essential in real applications.展开更多
Beam steering in implant defined coherently coupled vertical cavity surface emitting laser （VCSEL） arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences amo...Beam steering in implant defined coherently coupled vertical cavity surface emitting laser （VCSEL） arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences among elements, inter-element spacing, element size and emitted wavelength is analyzed detailedly and systematically. We design and fabricate 1×2 implant defined VCSEL arrays for optimum beam steering performance. Electroni- cally controlled beam steering with a maximum deflection angle of 1.6° is successfully achieved in the 1 × 2 VCSEL arrays. The percentage of the power in the central lobe is above 39% when steering. The results show that the steering is controllable. Compared with other beam steering methods, the fabrication process is simple and of low cost.展开更多
In this paper,we proposed and experimentally demonstrated an 8-channel O-band distributed feedback(DFB)laser array with highly uniform 400 GHz spacing and high output power for optical input/output(I/O)technology.The ...In this paper,we proposed and experimentally demonstrated an 8-channel O-band distributed feedback(DFB)laser array with highly uniform 400 GHz spacing and high output power for optical input/output(I/O)technology.The grating phase is precisely controlled,and an equivalentπphase shift is implemented in the laser cavity via the reconstruction equivalent chirp(REC)technology.Anti-reflection(AR)and high-reflection(HR)films are coated on the front and rear facets,respectively,to enhance output power.The equivalentπphase shift is strategically placed near the HR film facet to improve the yield of the single longitudinal mode.Operating with a 400 GHz wavelength spacing,the proposed DFB laser array meets the continuous wave-wavelength division multiplexing multi-source agreement(CW-WDM MSA)specifications.The proposed DFB laser array is flip-chip bonded to a thin-film circuit with an aluminum nitride(AlN)submount to reduce the thermal resistance and enhance the output power.Compared to the p-side-up structure,the flip-chip bonding design significantly reduces junction temperature by 28%and increases maximum output power by approximately 20%.This design effectively lowers the thermal resistance of the chip and enhances its heat dissipation properties.At a bias current of 110 mA,the laser demonstrates wavelength deviations below 1.579 GHz and side-mode suppression ratios above 50 dB.The far-field divergence is measured at 25.8°×30.1°,and the Lorentzian linewidth is 3.28 MHz.Increasing the bias current to250 mA results in a laser output power exceeding 80 mW.Furthermore,the relative intensity noise(RIN)for all 8 channels is below-135.3 d B/Hz.The proposed flip-chip bonded 8-channel high-power DFB laser array demonstrates uniform wavelength spacing,high output power,and stable single longitudinal mode performance,making it a promising candidate for multiple wavelength laser sources in optical I/O technology.展开更多
The optically levitated mechanical system in vacuum is a powerful platform in physics.It has been displaying more extensive application prospects.This paper presents an experimental study of optical levitation,identif...The optically levitated mechanical system in vacuum is a powerful platform in physics.It has been displaying more extensive application prospects.This paper presents an experimental study of optical levitation,identification,motion measurement,and assembly of two-species photoluminescence nanoparticles.A laser trapping array simultaneously levitates nitrogen-vacancy(NV)nanodiamonds and Yb^(3+)/Er^(3+):NaYF_(4)nanoparticles.The species of each nanoparticle can be individually identified by measuring the photoluminescence spectrum.We choose the single NV nanodiamond and Yb^(3+)/Er^(3+):NaYF_(4)nanoparticle and assemble them into a Janus composite nanoparticle,which integrates the merits of the two components.This work demonstrates the potential advantages of a hybrid optically levitated system.It provides a practicable scheme for the study of macroscopic quantum phenomena and precision measurement,thanks to the spin manipulation or spin-mechanical coupling of an NV diamond and by simultaneously implementing laser refrigeration to the Yb^(3+)/Er^(3+):NaYF_(4)nanoparticle in an optically levitated composite nanoparticle.展开更多
Truncation manipulation is a simple but effective way to improve the intensity distribution properties of the phase-locked Gaussian beam array at the receiving plane. In this paper, the analytical expression for the p...Truncation manipulation is a simple but effective way to improve the intensity distribution properties of the phase-locked Gaussian beam array at the receiving plane. In this paper, the analytical expression for the propagation of the phase-locked truncated Gaussian beam array in a turbulent atmosphere is obtained based on the extended Huygens--Fresnel principle. Power in the diffraction-limited bucket is introduced as the beam quality factor to evaluate the influence of different truncation parameters. The dependence of optimal truncation ratio on the number of beamlets, the intensity of turbulence, propagation distance and laser wavelength is calculated and discussed. It is revealed that the optimal truncation ratio is larger for the laser array that contains more lasers, and the optimal truncation ratio will shift to a larger value with an increase in propagation distance and decrease in intensity of atmosphere turbulence. The optimal truncation ratio is independent of laser wavelength.展开更多
Satellite laser ranging(SLR)is an unambiguous measurement technique and generates high accuracy satellite orbit data.All satellites in the BeiDou navigation satellite system(BDS)carried laser retro-reflector arrays(LR...Satellite laser ranging(SLR)is an unambiguous measurement technique and generates high accuracy satellite orbit data.All satellites in the BeiDou navigation satellite system(BDS)carried laser retro-reflector arrays(LRAs),so they can be tracked by ground SLR stations in order to provide the accurate observation data.The Shanghai astronomical observatory(SHAO)designed the LRAs,and also developed the dedicated SLR systems using a 1 m-aperture telescope and a transportable cabin-based SLR system with a telescopes of 60 cm aperture.These enable BDS satellite ranging during daytime and nighttime with centimeter-level precision,allowing highly accurate estimations of satellite orbits.Moreover,some of the BDS satellites are also equipped with laser time transfer(LTT)payloads,which were developed by the SHAO and China Academy of Space Technology(CAST),providing a highly accurate time comparison between the satellites and ground clocks.This paper describes the dedicated SLR system and the design of the LRAs for BDS satellites,as well as global SLR measurements.The SLR tracking data is used for evaluating the orbit accuracy of BDS satellites and broadcast ephemeris,with an accuracy of less than 1 m.The LTT measurements to BDS satellites for a single shot have a precision of approximately 300 picoseconds,with a time stability of 20 picoseconds in 500 s.展开更多
This paper presents an efficient scheme for single-pixel imaging(SPI)utilizing a phase-controlled fiber laser array and an untrained deep neural network.The fiber lasers are arranged in a compact hexagonal structure a...This paper presents an efficient scheme for single-pixel imaging(SPI)utilizing a phase-controlled fiber laser array and an untrained deep neural network.The fiber lasers are arranged in a compact hexagonal structure and coherently combined to generate illuminating light fields.Through the utilization of high-speed electro-optic modulators in each individual fiber laser module,the randomly modulated fiber laser array enables rapid speckle projection onto the object of interest.Furthermore,the untrained deep neural network is incorporated into the image reconstructing process to enhance the quality of the reconstructed images.Through simulations and experiments,we validate the feasibility of the proposed method and successfully achieve high-quality SPI utilizing the coherent fiber laser array at a sampling ratio of 1.6%.Given its potential for high emitting power and rapid modulation,the SPI scheme based on the fiber laser array holds promise for broad applications in remote sensing and other applicable fields.展开更多
Dynamic beam shaping is of importance for a wide range of applications, such as light field regulation, laser processing, and advanced manufacturing. In this paper, an internal phase-sensing tiled-aperture coherent be...Dynamic beam shaping is of importance for a wide range of applications, such as light field regulation, laser processing, and advanced manufacturing. In this paper, an internal phase-sensing tiled-aperture coherent beam-combining system with seven beam elements was constructed for dynamic beam shaping. This system could be performed as a digital laser,where each laser beamlet functioned as an individual laser pixel. The amplitude and phase of each laser pixel could be adjusted independently in real time. In our experiment, the laser array was operated in three different configurations:the triangular, pentagonal, and hexagonal laser arrays, while each laser pixel was modulated with a different piston phase of nπ(where n was an integer). We demonstrated various beam-shaping patterns based on this system with output powers scaling over 1 kW. Additionally, the energy distribution of the emitted laser could be flexibly varied and customized.These results highlighted that our dynamic beam-shaped laser exhibited excellent performance in both dynamic beam-shaping and power-scaling capabilities. This work holds great potential for numerous applications involving beam shaping.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62275272)the Training Program for Excellent Young Innovators of Changsha(Grant No.KQ2305025)。
文摘Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.
基金supported by National Basic Research Program of China(Grant Nos.2018YFA0209103,2018YFB2200504)in part by National Natural Science Foundation of China(Grant Nos.61991430,61774146,61790583,61734006,61835011,61674144,61774150,61805168)+1 种基金in part by Beijing Municipal Science&Technology Commission(Grant No.Z201100004020006)in part by the Key projects of the Chinese Academy of Sciences(Grant No.2018147,Grant No.YJKYYQ20190002,Grant No.QYZDJ-SSW-JSC027,Grant No.XDB43000000,Grant No.ZDKYYQ20200006).
文摘In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10°was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback(DFB)grating,substrate emission with a radiation power above 1 W at 25℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of -0.2 cm^(-1)/K.
基金Project supported by the National High Technology Research and Pevelopment Program of China (Grant Nos. 2011AA010303 and 2012AA012203)the National Basic Research Program of China (Grant No. 2011CB301702)the National Natural Science Foundation of China (Grant Nos. 61021003 and 61090392)
文摘Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback （DFB） lasers using varied ridge width with a 4 x 1-multimode-interference （MMI） optical combiner and a semiconductor optical amplifier （SOA） is demon- strated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio （SMSR） exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61376049,61076044,61107026,61204011and U1037602the Natural Science Foundation of Beijing under Grant Nos 4132006,4102003,and 4112006+1 种基金the Scientific Research Fund Project of Municipal Education Commission of Beijing under Grant No KM201210005004the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20121103110018
文摘A three-dimensional electrical-thermal coupling model based on the finite element method is applied to study thermal properties of implant-defined vertical cavity surface emitting laser （VCSEL） arrays. Several parameters including inter-element spacing, scales, injected current density and substrate temperature are considered. The actual temperatures obtained through experiment are in excellent agreement with the calculated results, which proves the accuracy of the model. Due to the serious thermal problem, it is essential to design arrays of low self-heating. The analysis can provide a foundation for designing VCSEL arrays in the future.
文摘According to our engineering research on satellite-borne laser retroreflector array, some suggestions are proposed on how to manufacture a new Apollo LLRA that can make us measure one illuminating point and unilluminating area on the moon's surface. These suggestions are: to control the dihedral angle offset within ± 0.1″; to use the larger aperture of the transparent face of cube corner prisms; to investigate how to separate out Apollo's reflected laser from mixed beam hitting on the LLR system.
文摘The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.
文摘The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61376049,61076044,61107026 and 61204011the Scientific Research Fund Project of Municipal Education Commission of Beijing under Grant No PXM2014-014204-07-000018
文摘Far-field properties dependent on array scale, separation, element width and emitted wavelength are system atically analyzed theoretically and experimentally. An array model based on the finite-difference method is established to simulate the far-field profile of the coherent arrays. Some important conclusions are obtained. To achieve a higher quality beam, it is necessary to decrease separation between elements, or to increase the element width. Higher brightness can be achieved in the array with larger scale. Emitted wavelength also has an influence on the far-field profile. These analyses can be extended to the future design of coherent vertical cavity surface emitting laser arrays.
基金supported by the National Natural Science Foundation of China (Nos.61674142 and 62041502)。
文摘In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric turbulence. A prototype of the proposed structure is fabricated and a 2.5 Mbit/s on-off keying(OOK) modulated demonstration link over 40 m free space is built. This asymmetric array structure can effectively collect optical signal while rotating in a window angle of ±17°, and the bit error ratio(BER) keeps zero.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFB0402002,2016YFB0401803,2017YFB0405002,2017YFB0405003,and 2017YFB0405005)the National Natural Science Foundation of China(Grant Nos.61574160,61704184,and 61334005)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Science(Grant No.XDA09020401)the Chinese Academy of Science Visiting Professorship for Senior International Scientists(Grant No.2013T2J0048)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20170430)the CPSF-CAS Joint Foundation for Excellent Postdoctoral Fellows,China(Grant No.2016LH0026)
文摘Thermal characteristics of multiple laser stripes integrated into one chip is investigated theoretically in this paper. The temperature pattern of the laser diode mini-array packaged in a TO-can is analyzed and optimized to achieve a uniform temperature distribution among the laser stripes and along the cavity direction. The temperature among the laser stripes varies by more than 5 K if the stripes are equally arranged, and can be reduced to less than 0.4 K if proper arrangement is designed. For conventional submount structure, the temperature variation along the cavity direction is as high as 7 K, while for an optimized trapezoid submount structure, the temperature varies only within 0.5 K.
文摘A diode laser array(DLA)positioned in an external cavity can receive the radiations emitted from its neighboring elements (C 1) and that of itself (S) after being reflected at the DLA facet as well as from the external mirror (C 0). Considering the fact that｜C 0/S｜ should be larger than unity if the external cavity is effective,and｜C 1/S｜ should be larger than unity if the phase locking may be established in the external cavity.The requirements on the reflection at the facet of the diode laser array have been specified in terms of the cavity length and reflection coefficient of the external mirror.
文摘We report one thick layer of hard-baked photoresist mask.The laser array stripe pattern was defined by standard wet lithography.With this mask, a 10 W QCW(quasi-continuous wave) operation of a narrow proton implanted multiple stripe conventional single quantum well separate confinement heterostructure(SQW-SCH) GaAlAs diode laser array has been realized.These devices exhibit the lateral far-field radiation pattern of a phase-locked array of gain-guided semiconductor injection laser array.The twenty stripe laser array has a lateral far-field beam divergence full width at half maximum(FWHM) of less than 3°,and three twenty stripe laser array has a beam divergence in the plane of the junction of about 9°.
基金Supported by the National Basic Research Program of China under Grant No 2013CB632801the National Key Research and Development Program of China under Grant No 2016YFB0402303+2 种基金the National Natural Science Foundation of China under Grant Nos 61435014,61627822,61574136,61306058 and 61404131the Key Projects of Chinese Academy of Sciences under Grant No ZDRW-XH-2016-4the Beijing Natural Science Foundation under Grant No 4162060
文摘An external cavity quantum cascade laser （QCL） array with a wide tuning range and high output power is pre- sented. The coherent QCL array combined with a diffraction grating and gold mirror is tuned in the Littrow configuration. Taking advantage of the single-lobed fundamental supermode far-field pattern, the tuning capa- bility of 30.6cm-1 is achieved with a fixed injected current of 3.5 A at room temperature. Single-mode emission can be observed in the entire process. The maximum single-mode output power of the external cavity setup is as high as 25mW and is essential in real applications.
基金Supported by the‘Supporting First Action’Joint Foundation for Outstanding Postdoctoral Program under Grant Nos Y7YBSH0001 and Y7BSH14001the National Natural Science Foundation of China under Grant No 61434006the National Key Basic Research Program of China under Grant No 2017YFB0102302
文摘Beam steering in implant defined coherently coupled vertical cavity surface emitting laser （VCSEL） arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences among elements, inter-element spacing, element size and emitted wavelength is analyzed detailedly and systematically. We design and fabricate 1×2 implant defined VCSEL arrays for optimum beam steering performance. Electroni- cally controlled beam steering with a maximum deflection angle of 1.6° is successfully achieved in the 1 × 2 VCSEL arrays. The percentage of the power in the central lobe is above 39% when steering. The results show that the steering is controllable. Compared with other beam steering methods, the fabrication process is simple and of low cost.
基金supported by the National Natural Science Foundation of China(No.62404098)the Natural Science Foundation of Jiangsu Province of China(No.BK20241196)the National Key Research and Development Program of China(Nos.2023YFB2806400,2021YFB2801902,and 2018YFB2201801)。
文摘In this paper,we proposed and experimentally demonstrated an 8-channel O-band distributed feedback(DFB)laser array with highly uniform 400 GHz spacing and high output power for optical input/output(I/O)technology.The grating phase is precisely controlled,and an equivalentπphase shift is implemented in the laser cavity via the reconstruction equivalent chirp(REC)technology.Anti-reflection(AR)and high-reflection(HR)films are coated on the front and rear facets,respectively,to enhance output power.The equivalentπphase shift is strategically placed near the HR film facet to improve the yield of the single longitudinal mode.Operating with a 400 GHz wavelength spacing,the proposed DFB laser array meets the continuous wave-wavelength division multiplexing multi-source agreement(CW-WDM MSA)specifications.The proposed DFB laser array is flip-chip bonded to a thin-film circuit with an aluminum nitride(AlN)submount to reduce the thermal resistance and enhance the output power.Compared to the p-side-up structure,the flip-chip bonding design significantly reduces junction temperature by 28%and increases maximum output power by approximately 20%.This design effectively lowers the thermal resistance of the chip and enhances its heat dissipation properties.At a bias current of 110 mA,the laser demonstrates wavelength deviations below 1.579 GHz and side-mode suppression ratios above 50 dB.The far-field divergence is measured at 25.8°×30.1°,and the Lorentzian linewidth is 3.28 MHz.Increasing the bias current to250 mA results in a laser output power exceeding 80 mW.Furthermore,the relative intensity noise(RIN)for all 8 channels is below-135.3 d B/Hz.The proposed flip-chip bonded 8-channel high-power DFB laser array demonstrates uniform wavelength spacing,high output power,and stable single longitudinal mode performance,making it a promising candidate for multiple wavelength laser sources in optical I/O technology.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.61975101,11234008,11361161002,and 6157-1276)。
文摘The optically levitated mechanical system in vacuum is a powerful platform in physics.It has been displaying more extensive application prospects.This paper presents an experimental study of optical levitation,identification,motion measurement,and assembly of two-species photoluminescence nanoparticles.A laser trapping array simultaneously levitates nitrogen-vacancy(NV)nanodiamonds and Yb^(3+)/Er^(3+):NaYF_(4)nanoparticles.The species of each nanoparticle can be individually identified by measuring the photoluminescence spectrum.We choose the single NV nanodiamond and Yb^(3+)/Er^(3+):NaYF_(4)nanoparticle and assemble them into a Janus composite nanoparticle,which integrates the merits of the two components.This work demonstrates the potential advantages of a hybrid optically levitated system.It provides a practicable scheme for the study of macroscopic quantum phenomena and precision measurement,thanks to the spin manipulation or spin-mechanical coupling of an NV diamond and by simultaneously implementing laser refrigeration to the Yb^(3+)/Er^(3+):NaYF_(4)nanoparticle in an optically levitated composite nanoparticle.
基金supported by the Innovation Foundation for Postgraduate of Hunan Province
文摘Truncation manipulation is a simple but effective way to improve the intensity distribution properties of the phase-locked Gaussian beam array at the receiving plane. In this paper, the analytical expression for the propagation of the phase-locked truncated Gaussian beam array in a turbulent atmosphere is obtained based on the extended Huygens--Fresnel principle. Power in the diffraction-limited bucket is introduced as the beam quality factor to evaluate the influence of different truncation parameters. The dependence of optimal truncation ratio on the number of beamlets, the intensity of turbulence, propagation distance and laser wavelength is calculated and discussed. It is revealed that the optimal truncation ratio is larger for the laser array that contains more lasers, and the optimal truncation ratio will shift to a larger value with an increase in propagation distance and decrease in intensity of atmosphere turbulence. The optimal truncation ratio is independent of laser wavelength.
基金supported by the BDS and the National Natural Science Foundation of China(Grant No.11503068,U1631240)Shanghai Key Laboratory of Space Navigation and Position Techniques(Grant No.06DZ2101)+2 种基金CAS Key Technology Talent ProgramNatural science fund of Shanghai(20ZR1467500)the Key Research Program of the Chinese Academy of Sciences(ZDRW-KT-2019-3-6)。
文摘Satellite laser ranging(SLR)is an unambiguous measurement technique and generates high accuracy satellite orbit data.All satellites in the BeiDou navigation satellite system(BDS)carried laser retro-reflector arrays(LRAs),so they can be tracked by ground SLR stations in order to provide the accurate observation data.The Shanghai astronomical observatory(SHAO)designed the LRAs,and also developed the dedicated SLR systems using a 1 m-aperture telescope and a transportable cabin-based SLR system with a telescopes of 60 cm aperture.These enable BDS satellite ranging during daytime and nighttime with centimeter-level precision,allowing highly accurate estimations of satellite orbits.Moreover,some of the BDS satellites are also equipped with laser time transfer(LTT)payloads,which were developed by the SHAO and China Academy of Space Technology(CAST),providing a highly accurate time comparison between the satellites and ground clocks.This paper describes the dedicated SLR system and the design of the LRAs for BDS satellites,as well as global SLR measurements.The SLR tracking data is used for evaluating the orbit accuracy of BDS satellites and broadcast ephemeris,with an accuracy of less than 1 m.The LTT measurements to BDS satellites for a single shot have a precision of approximately 300 picoseconds,with a time stability of 20 picoseconds in 500 s.
文摘This paper presents an efficient scheme for single-pixel imaging(SPI)utilizing a phase-controlled fiber laser array and an untrained deep neural network.The fiber lasers are arranged in a compact hexagonal structure and coherently combined to generate illuminating light fields.Through the utilization of high-speed electro-optic modulators in each individual fiber laser module,the randomly modulated fiber laser array enables rapid speckle projection onto the object of interest.Furthermore,the untrained deep neural network is incorporated into the image reconstructing process to enhance the quality of the reconstructed images.Through simulations and experiments,we validate the feasibility of the proposed method and successfully achieve high-quality SPI utilizing the coherent fiber laser array at a sampling ratio of 1.6%.Given its potential for high emitting power and rapid modulation,the SPI scheme based on the fiber laser array holds promise for broad applications in remote sensing and other applicable fields.
基金supported by the National Natural Science Foundation of China (No.62275272)the Training Program for Excellent Young Innovators of Changsha(No.kq2205025)。
文摘Dynamic beam shaping is of importance for a wide range of applications, such as light field regulation, laser processing, and advanced manufacturing. In this paper, an internal phase-sensing tiled-aperture coherent beam-combining system with seven beam elements was constructed for dynamic beam shaping. This system could be performed as a digital laser,where each laser beamlet functioned as an individual laser pixel. The amplitude and phase of each laser pixel could be adjusted independently in real time. In our experiment, the laser array was operated in three different configurations:the triangular, pentagonal, and hexagonal laser arrays, while each laser pixel was modulated with a different piston phase of nπ(where n was an integer). We demonstrated various beam-shaping patterns based on this system with output powers scaling over 1 kW. Additionally, the energy distribution of the emitted laser could be flexibly varied and customized.These results highlighted that our dynamic beam-shaped laser exhibited excellent performance in both dynamic beam-shaping and power-scaling capabilities. This work holds great potential for numerous applications involving beam shaping.
