A new technology for fabrication of silica on silicon arrayed waveguide grating (AWG) based on deep etching and thermal oxidation is presented.Using this method,a silicon layer is remained at the side of waveguide.The...A new technology for fabrication of silica on silicon arrayed waveguide grating (AWG) based on deep etching and thermal oxidation is presented.Using this method,a silicon layer is remained at the side of waveguide.The stress distribution and effective refractive index of waveguide fabricated by this approach are calculated using finite element and finite difference beam propagation method,respectively.The results of these studies indicate that the stress of silica on silicon optical waveguide can be matched in parallel and vertical direction and AWG polarization dependent wavelength (PDλ) can be reduced effectively due to side-silicon layer.展开更多
The fact that the signal results in signal―crosstalk is confirmed forarrayed―waveguide grating as NXN optical router, and the relation between the crosstalk and powerpenalty is obtained. The method reveals the rando...The fact that the signal results in signal―crosstalk is confirmed forarrayed―waveguide grating as NXN optical router, and the relation between the crosstalk and powerpenalty is obtained. The method reveals the random distributions of optical path phase errors in twomultiplexers with channel numbers of 10 and 160. It is shown that the crosstalk must be less than―28 dB for a power penalty below 1 dB at a bit error rate of 1X10^(-9). It is found that when N =100, crosstalk power value is ? 20 dB with compensation power of 2―3 dB, so the compensation poweris not ignored.展开更多
Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arr...Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arrayed waveguide.An approach of compensating TE TM mode polarization is presented by using the phase difference,which is caused by TIR at the waveguide mirror.This AWG device has advantage for its small size and simple technigue of fabrication.The experimental results are given and the feasibility of fabrication is tested.展开更多
A novel design of 100GHz-spaced 16channel arrayed-waveguide grating (AWG) based on silica-on-silicon chip is reported.AWG is achieved by adding a Y-branch to the AWG and arranging the input/output channel in a neat ro...A novel design of 100GHz-spaced 16channel arrayed-waveguide grating (AWG) based on silica-on-silicon chip is reported.AWG is achieved by adding a Y-branch to the AWG and arranging the input/output channel in a neat row,so the whole configuration can be aligned and packaged using only one fiber-array.This configuration can decrease the device’s size,enlarge the minimum radius of curvature,save time on polishing and alignment,and reduce the chip’s fabrication cost.展开更多
In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide a...In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.展开更多
A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings(AWGs).It has a parallel structure consisting of two silicon 16-channe...A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings(AWGs).It has a parallel structure consisting of two silicon 16-channel AWGs with200 GHz spacing and a Mach-Zehnder interferometer(MZI)with 200 GHz free spectral range.The 16 channels of one silicon AWG are interleaved with those of the other AWG in spectrum,but with an identical spacing of 200 GHz.For the composed wavelength division multiplexer,the experiment results reveal 32 wavelength channels in C-band,a wavelength spacing of 100 GHz,and a channel crosstalk lower than-15 dB.展开更多
We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13- channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometr...We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13- channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refrac- tive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickfiess of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick match.ing layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W.展开更多
In this letter,a fiber Bragg grating(FBG)dynamic strain sensing system using a semiconductor optical amplifier(SOA)-fiber ring laser(FRL)and an arrayed waveguide grating(AWG)demodulator is proposed.Due to the characte...In this letter,a fiber Bragg grating(FBG)dynamic strain sensing system using a semiconductor optical amplifier(SOA)-fiber ring laser(FRL)and an arrayed waveguide grating(AWG)demodulator is proposed.Due to the characteristics of SOA,it can act as the gain medium as well as light source.The AWG module is used as the wavelength demodulator.It is shown that SOA-based FRL sensors can accurately respond to 1.5μεdynamic strain signal with high frequency up to 120 k Hz and almost no distortion in the waveforms.Experimental results show that the system can be used for acoustic testing,such as underwater ultrasonic detection and external impact monitoring.In addition,the simultaneous dual-channel demodulated system is investigated in detail to verify the multiplexing.This dynamic strain sensing system can be widely utilized in structural health monitoring because of its high stability,low cost and good multiplexability.展开更多
The operation principle of an arrayed waveguide grating(AWG) multiplexer is introduced and the 4×4 AWG with following design parameters is discussed in detail, such as the choice of wavelength, the neighboring ar...The operation principle of an arrayed waveguide grating(AWG) multiplexer is introduced and the 4×4 AWG with following design parameters is discussed in detail, such as the choice of wavelength, the neighboring arrayed waveguide distance ΔL, the channel frequency interval Δf, and the free spectral range. The structure of 4×4 AWG is designed and the result of stimulated test is also given. Analysis shows that the 4×4 AWG is characterized by a wide dynamic range, low crosstalk, better spectrum properties, and a compact structure.展开更多
A 13-channel, InP-based arrayed waveguide grating （AWG） is designed and fabricated in which the on-chip loss of the central channel is about -5 dB and the crosstalk is less than -23 dB in the center of the spectrum ...A 13-channel, InP-based arrayed waveguide grating （AWG） is designed and fabricated in which the on-chip loss of the central channel is about -5 dB and the crosstalk is less than -23 dB in the center of the spectrum response. However, the central wavelength and channel spacing are deviated from the design values. To improve their accuracy, an optimized design is adopted to compensate the process error. As a result, the central wavelength 1549.9 nm and channel spacing 1.59 nm are obtained in the experiment, while their design values are 1549.32 nm and 1.6 nm, respectively. The route capability and thermo-optic characteristic of the AWG are also discussed in detail.展开更多
The improved performance of a wavelength-tunable arrayed waveguide grating (AWG) is demonstrated, including the crosstalk, insertion loss and the wavelength tuning efficiency. A reduced impact of the fabrication proce...The improved performance of a wavelength-tunable arrayed waveguide grating (AWG) is demonstrated, including the crosstalk, insertion loss and the wavelength tuning efficiency. A reduced impact of the fabrication process on the AWG is achieved by the design of bi-level tapers. The wavelength tuning of the AWG is achieved according to the thermo-optic effect of silicon, and uniform heating of the silicon waveguide layer is achieved by optimizing the heater design. The fabricated AWG shows a minimum crosstalk of 16 dB, a maximum insertion loss of 3.91 dB and a wavelength tuning efficiency of 8.92 nm/W, exhibiting a ～8 dB improvement of crosstalk, ～2.1 dB improvement of insertion loss and ～5 nm/W improvement of wavelength tuning efficiency, compared to our previous reported results.展开更多
A cross-linkable fluorinated poly (ether ether ketone) (FPEEK) was synthesized for the fabrication of arrayed waveguide grating (AWG) multiplexer. The results of thermal gravimetric analysis (TGA) and near-infrared ab...A cross-linkable fluorinated poly (ether ether ketone) (FPEEK) was synthesized for the fabrication of arrayed waveguide grating (AWG) multiplexer. The results of thermal gravimetric analysis (TGA) and near-infrared absorption spectrum show that the materials have high thermal stability and high optical transparency in the infrared communication region. The refractive index of FPEEK can be controlled easily by changing the fluorine content of the materials. The 32-channel AWG multiplexer is fabricated using the FPEEK and oxygen reactive ion etching technology. The AWG multiplexer exhibits that the insertion loss is from 12.8 to 17.8 dB and the channel crosstalk is less than-20 dB. The wavelength channel spacing and the center wavelength are 0.8nm and 1548nm, respectively.展开更多
A four-channel 400 GHz channel spacing InP-based arrayed waveguide grating with a flattened wavelength re- sponse by employing a multimode interference coupler at the input waveguide of the filter is prepared. The fab...A four-channel 400 GHz channel spacing InP-based arrayed waveguide grating with a flattened wavelength re- sponse by employing a multimode interference coupler at the input waveguide of the filter is prepared. The fabricated devices show a flattened spectral response with a broadened 3-dB bandwidth up to 3.5 nm, interchan- nel non-uniformity of 〈0. 7dB and excellent match to the simulation results.展开更多
A novel approach devoted to achieving ultra-wideband radar cross section reduction（RCSR） of a waveguide slot antenna array（WGSAA） while maintaining its radiation performance is proposed. Three kinds of artificial ...A novel approach devoted to achieving ultra-wideband radar cross section reduction（RCSR） of a waveguide slot antenna array（WGSAA） while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors（AMCs） tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.展开更多
Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found t...Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found that the coupling efficiency is sensitive to the interval, the total number and the quality factor of the resonator. Considering the coupling efficiency and the coupling region, we select five resonators with an interval of six lattice periods. By optimizing the structure parameters of the waveguide and resonator, the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory. Compared with other coupling methods, the side-coupled waveguide can realize efficient coupling with a compact structure, a high level of integration and a low degree of operational difficulties.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
In conventional High Power Microwave(HPM)waveguide arrays of longitudinal shunt slots,the mutual coupling of slots in different waveguide can badly decrease the capability of wide-angle scanning of array.For this reas...In conventional High Power Microwave(HPM)waveguide arrays of longitudinal shunt slots,the mutual coupling of slots in different waveguide can badly decrease the capability of wide-angle scanning of array.For this reason,an L-band HPM waveguide array of longitudinal shunt slots was designed.The choke groove was adopted to restrain the mutual coupling of slots of the HPM array antenna.The results of simulation are:the scanning angle of array without choke groove structure with the gain of antenna decreased 3 dB is only 24.7°,and it is 33.0°for array with choke groove structure;the wideband of active reflection of array have been improved with choke groove structure,the bandwidth of VSWR≤3 of array with choke groove is 6.6%,and that is 5.0%without choke groove;the power-handling capacity of array antenna with scanning angle of 35°can reach 957 MW,which is a little less than that of array without scanning(1008MW).展开更多
In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized plan...In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.展开更多
The inhomogenous ocean waveguide,which leads the amplitude and phase of the signal arriving at a hydrophone array to fluctuate,is one of the causes that make the array gain deviate from its ideal value.The relationshi...The inhomogenous ocean waveguide,which leads the amplitude and phase of the signal arriving at a hydrophone array to fluctuate,is one of the causes that make the array gain deviate from its ideal value.The relationship between the array gain and the fluctuant acoustic channel is studied theoretically.The analytical expression of the array gain is derived via an acoustic channel transfer function on the assumption that the ambient noise field is isotropic.The expression is expanded via the Euler formula to give an insight into the effect of the fluctuant acoustic channel on the array gain.The result demonstrates that the amplitude fluctuation of the acoustic channel transfer functions has a slight effect on the array gain;however,the uniformity of the phase difference between the weighting coefficient and the channel transfer function on all the hydrophones in the array is a major factor that leads the array gain to further deviate from its ideal value.The numerical verification is conducted in the downslope waveguide,in which the gain of a horizontal uniform linear array(HLA)with a wide-aperture operating in the continental slope area is considered.Numerical result is consistent with the theoretical analysis.展开更多
The alignment coupling between optical waveguide chips and optical fiber arrays is the basis of the alignment coupling of planar optical waveguide devices, and the precise position detection with angle and spacing adj...The alignment coupling between optical waveguide chips and optical fiber arrays is the basis of the alignment coupling of planar optical waveguide devices, and the precise position detection with angle and spacing adjustments is one of the key steps of alignment coupling. A methodology for position detection, and angle and spacing adjustment was proposed for optical waveguide chips and optical fiber arrays based on machine vision. The experimental results show angle detection precision levels higher than 0.05°, line detection precision levels higher than 0.1 μm, and detection time less than 2 s. Therefore, the system developed herein meets the precise requirements necessary for position detection, and angle and spacing adjustments for optical waveguide chips and optical fiber arrays.展开更多
文摘A new technology for fabrication of silica on silicon arrayed waveguide grating (AWG) based on deep etching and thermal oxidation is presented.Using this method,a silicon layer is remained at the side of waveguide.The stress distribution and effective refractive index of waveguide fabricated by this approach are calculated using finite element and finite difference beam propagation method,respectively.The results of these studies indicate that the stress of silica on silicon optical waveguide can be matched in parallel and vertical direction and AWG polarization dependent wavelength (PDλ) can be reduced effectively due to side-silicon layer.
文摘The fact that the signal results in signal―crosstalk is confirmed forarrayed―waveguide grating as NXN optical router, and the relation between the crosstalk and powerpenalty is obtained. The method reveals the random distributions of optical path phase errors in twomultiplexers with channel numbers of 10 and 160. It is shown that the crosstalk must be less than―28 dB for a power penalty below 1 dB at a bit error rate of 1X10^(-9). It is found that when N =100, crosstalk power value is ? 20 dB with compensation power of 2―3 dB, so the compensation poweris not ignored.
文摘Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arrayed waveguide.An approach of compensating TE TM mode polarization is presented by using the phase difference,which is caused by TIR at the waveguide mirror.This AWG device has advantage for its small size and simple technigue of fabrication.The experimental results are given and the feasibility of fabrication is tested.
文摘A novel design of 100GHz-spaced 16channel arrayed-waveguide grating (AWG) based on silica-on-silicon chip is reported.AWG is achieved by adding a Y-branch to the AWG and arranging the input/output channel in a neat row,so the whole configuration can be aligned and packaged using only one fiber-array.This configuration can decrease the device’s size,enlarge the minimum radius of curvature,save time on polishing and alignment,and reduce the chip’s fabrication cost.
基金supported by the National Natural Science Foundation of China(No.62375031)the Basic Research Project of Chongqing Science and Technology Commission(No.CSTC-2021jcyj-bsh0194)the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202200602)。
文摘In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.
基金Project supported by the National Key Research and Development Program of China(Grant No.2019YFB2203600)。
文摘A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings(AWGs).It has a parallel structure consisting of two silicon 16-channel AWGs with200 GHz spacing and a Mach-Zehnder interferometer(MZI)with 200 GHz free spectral range.The 16 channels of one silicon AWG are interleaved with those of the other AWG in spectrum,but with an identical spacing of 200 GHz.For the composed wavelength division multiplexer,the experiment results reveal 32 wavelength channels in C-band,a wavelength spacing of 100 GHz,and a channel crosstalk lower than-15 dB.
基金Project supported by the National High Technology Research and Development Program of China(Grant Nos.2013AA031401,2015AA016902,and 2015AA016904)the National Natural Science Foundation of China(Grant Nos.61176053,61274069,and 61435002)the National Basic Research Program of China(Grant Nos.2012CB933503 and 2013CB932904)
文摘We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13- channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refrac- tive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickfiess of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick match.ing layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W.
基金supported by the National Natural Science Foundation of China(No.51874064)the Project of Graduate Innovation in Chongqing University of Technology(No.gzlcx20223295)。
文摘In this letter,a fiber Bragg grating(FBG)dynamic strain sensing system using a semiconductor optical amplifier(SOA)-fiber ring laser(FRL)and an arrayed waveguide grating(AWG)demodulator is proposed.Due to the characteristics of SOA,it can act as the gain medium as well as light source.The AWG module is used as the wavelength demodulator.It is shown that SOA-based FRL sensors can accurately respond to 1.5μεdynamic strain signal with high frequency up to 120 k Hz and almost no distortion in the waveforms.Experimental results show that the system can be used for acoustic testing,such as underwater ultrasonic detection and external impact monitoring.In addition,the simultaneous dual-channel demodulated system is investigated in detail to verify the multiplexing.This dynamic strain sensing system can be widely utilized in structural health monitoring because of its high stability,low cost and good multiplexability.
文摘The operation principle of an arrayed waveguide grating(AWG) multiplexer is introduced and the 4×4 AWG with following design parameters is discussed in detail, such as the choice of wavelength, the neighboring arrayed waveguide distance ΔL, the channel frequency interval Δf, and the free spectral range. The structure of 4×4 AWG is designed and the result of stimulated test is also given. Analysis shows that the 4×4 AWG is characterized by a wide dynamic range, low crosstalk, better spectrum properties, and a compact structure.
基金Project supported by the National High Technology Research and Development Program of China(Grant Nos.2011AA010303 and 2013AA031401)the National Natural Science Foundation of China(Grant No.61090390)
文摘A 13-channel, InP-based arrayed waveguide grating （AWG） is designed and fabricated in which the on-chip loss of the central channel is about -5 dB and the crosstalk is less than -23 dB in the center of the spectrum response. However, the central wavelength and channel spacing are deviated from the design values. To improve their accuracy, an optimized design is adopted to compensate the process error. As a result, the central wavelength 1549.9 nm and channel spacing 1.59 nm are obtained in the experiment, while their design values are 1549.32 nm and 1.6 nm, respectively. The route capability and thermo-optic characteristic of the AWG are also discussed in detail.
基金Supported by the National Key R&D Program of China under Grant No 2016YFB0402504
文摘The improved performance of a wavelength-tunable arrayed waveguide grating (AWG) is demonstrated, including the crosstalk, insertion loss and the wavelength tuning efficiency. A reduced impact of the fabrication process on the AWG is achieved by the design of bi-level tapers. The wavelength tuning of the AWG is achieved according to the thermo-optic effect of silicon, and uniform heating of the silicon waveguide layer is achieved by optimizing the heater design. The fabricated AWG shows a minimum crosstalk of 16 dB, a maximum insertion loss of 3.91 dB and a wavelength tuning efficiency of 8.92 nm/W, exhibiting a ～8 dB improvement of crosstalk, ～2.1 dB improvement of insertion loss and ～5 nm/W improvement of wavelength tuning efficiency, compared to our previous reported results.
文摘A cross-linkable fluorinated poly (ether ether ketone) (FPEEK) was synthesized for the fabrication of arrayed waveguide grating (AWG) multiplexer. The results of thermal gravimetric analysis (TGA) and near-infrared absorption spectrum show that the materials have high thermal stability and high optical transparency in the infrared communication region. The refractive index of FPEEK can be controlled easily by changing the fluorine content of the materials. The 32-channel AWG multiplexer is fabricated using the FPEEK and oxygen reactive ion etching technology. The AWG multiplexer exhibits that the insertion loss is from 12.8 to 17.8 dB and the channel crosstalk is less than-20 dB. The wavelength channel spacing and the center wavelength are 0.8nm and 1548nm, respectively.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61274046,61201103,61335009 and61320106013the National Basic Research Program of China under Grant No 2013AA014202
文摘A four-channel 400 GHz channel spacing InP-based arrayed waveguide grating with a flattened wavelength re- sponse by employing a multimode interference coupler at the input waveguide of the filter is prepared. The fabricated devices show a flattened spectral response with a broadened 3-dB bandwidth up to 3.5 nm, interchan- nel non-uniformity of 〈0. 7dB and excellent match to the simulation results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61671464,61701523,and 61471389)
文摘A novel approach devoted to achieving ultra-wideband radar cross section reduction（RCSR） of a waveguide slot antenna array（WGSAA） while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors（AMCs） tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60877031)
文摘Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found that the coupling efficiency is sensitive to the interval, the total number and the quality factor of the resonator. Considering the coupling efficiency and the coupling region, we select five resonators with an interval of six lattice periods. By optimizing the structure parameters of the waveguide and resonator, the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory. Compared with other coupling methods, the side-coupled waveguide can realize efficient coupling with a compact structure, a high level of integration and a low degree of operational difficulties.
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.
文摘In conventional High Power Microwave(HPM)waveguide arrays of longitudinal shunt slots,the mutual coupling of slots in different waveguide can badly decrease the capability of wide-angle scanning of array.For this reason,an L-band HPM waveguide array of longitudinal shunt slots was designed.The choke groove was adopted to restrain the mutual coupling of slots of the HPM array antenna.The results of simulation are:the scanning angle of array without choke groove structure with the gain of antenna decreased 3 dB is only 24.7°,and it is 33.0°for array with choke groove structure;the wideband of active reflection of array have been improved with choke groove structure,the bandwidth of VSWR≤3 of array with choke groove is 6.6%,and that is 5.0%without choke groove;the power-handling capacity of array antenna with scanning angle of 35°can reach 957 MW,which is a little less than that of array without scanning(1008MW).
文摘In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.
基金Project supported by the National Natural Science Foundation of China(Grant No.11534009)
文摘The inhomogenous ocean waveguide,which leads the amplitude and phase of the signal arriving at a hydrophone array to fluctuate,is one of the causes that make the array gain deviate from its ideal value.The relationship between the array gain and the fluctuant acoustic channel is studied theoretically.The analytical expression of the array gain is derived via an acoustic channel transfer function on the assumption that the ambient noise field is isotropic.The expression is expanded via the Euler formula to give an insight into the effect of the fluctuant acoustic channel on the array gain.The result demonstrates that the amplitude fluctuation of the acoustic channel transfer functions has a slight effect on the array gain;however,the uniformity of the phase difference between the weighting coefficient and the channel transfer function on all the hydrophones in the array is a major factor that leads the array gain to further deviate from its ideal value.The numerical verification is conducted in the downslope waveguide,in which the gain of a horizontal uniform linear array(HLA)with a wide-aperture operating in the continental slope area is considered.Numerical result is consistent with the theoretical analysis.
基金Projects(51475479,51075402)supported by the National Natural Science Foundation of ChinaProject(2012AA040406)supported by the National High Technology Research and Development Program of China+2 种基金Project(20110162130004)supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(14JJ2010)supported by the Natural Science Foundation of Hunan Province,ChinaProject(GZKF-201401)supported by the Open Project of Stage Key Laboratory of Fluid Power Transmission and Control(Zhejiang University),China
文摘The alignment coupling between optical waveguide chips and optical fiber arrays is the basis of the alignment coupling of planar optical waveguide devices, and the precise position detection with angle and spacing adjustments is one of the key steps of alignment coupling. A methodology for position detection, and angle and spacing adjustment was proposed for optical waveguide chips and optical fiber arrays based on machine vision. The experimental results show angle detection precision levels higher than 0.05°, line detection precision levels higher than 0.1 μm, and detection time less than 2 s. Therefore, the system developed herein meets the precise requirements necessary for position detection, and angle and spacing adjustments for optical waveguide chips and optical fiber arrays.
