In this paper,an efficient Ge_(25)Sb_(10)S_(65)(GeSbS)-loaded erbium-doped lithium niobate waveguide amplifier is demonstrated.By dimensional optimization of the waveguide,an internal net gain of approximately 28 dB a...In this paper,an efficient Ge_(25)Sb_(10)S_(65)(GeSbS)-loaded erbium-doped lithium niobate waveguide amplifier is demonstrated.By dimensional optimization of the waveguide,an internal net gain of approximately 28 dB and a maximum on-chip output power of 8.2 dBm are demonstrated upon 1480 nm bidirectional pumping.Due to the improved optical mode field distribution within the active erbium-doped lithium niobate film and the mode overlap ratio between the pump and signal sources,a 15% high conversion efficiency can be achieved at a modest pump power of 45 mW.Furthermore,the noise figure of the amplifier can be maintained below 6 dB for low-input-signal power levels.Compared to state-of-the-art erbium-doped waveguide amplifiers(EDWAs),this heterogeneously integrated device shows superior gain performance at the desired optical C-band while avoiding the complex plasma etching process of lithium niobate,providing an inspirative solution for power compensation in the optical telecommunications.展开更多
Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises amon...Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises among resolution,speed,and accuracy.Optical frequency combs are widely used for metrology of discrete atomic and molecular spectral lines.However,they are usually generated by optical methods and have large comb spacing,which limits the resolution for direct sampling of continuous spectra.To overcome these problems,this paper presents an original method to digitally generate an ultrafine optical frequency comb(UFOFC)as the frequency ruler for spectral measurements.Each comb line provides one sampling point,and the full spectrum can be captured at the same time using coherent detection.For an experimental demonstration,we adopted the inverse fast Fourier transform to generate a UFOFC with a comb spacing of 1.46 MHz over a 10-GHz range and demonstrated its functions using a Mach–Zehnder refractive index sensor.The UFOFC obtains a spectral resolution of 0.01 pm and response time of 0.7 μs;both represent 100-fold improvements over the state of the art and could be further enhanced by several orders of magnitude.The UFOFC presented here could facilitate new label-free sensor applications that require both high resolution and fast speed,such as measuring binding kinetics and single-molecule dynamics.展开更多
We propose the modified Kalman filter(MKF) using the received signal for observation and constructing an inverse process of the conventional Kalman filter(CKF) for polarization de-multiplexing in coherent optical(CO) ...We propose the modified Kalman filter(MKF) using the received signal for observation and constructing an inverse process of the conventional Kalman filter(CKF) for polarization de-multiplexing in coherent optical(CO) orthogonal frequency-division multiplexing(OFDM) transmissions. The MKF can avoid the convergence error problem in CKF without matrix inverse operation and has a faster converging speed and a much larger tolerance to the process and measurement noise covariance, about two orders of magnitude more than those of CKF. We experimentally demonstrate the 12 Gbaud OFDM signal transmission over 480 km standard singlemode fiber. The performance of MKF and CKF outperforms pilot-aided polarization de-multiplexing with better accuracy and nonlinearity tolerance.展开更多
Kalman filtering(KF) has good potential in fast rotation of state of polarization(RSOP) tracking. Different measurement equations cause the diverse RSOP tracking performances. We compare the conventional KF(CKF) and t...Kalman filtering(KF) has good potential in fast rotation of state of polarization(RSOP) tracking. Different measurement equations cause the diverse RSOP tracking performances. We compare the conventional KF(CKF) and the modified KF(MKF), which have different measurement equations. Semi-theoretical analysis indicates the lower conditional variances of measurement residuals and process noise of MKF. Compared with CKF, the MKF has > 3 d B optical signal-to-noise ratio(OSNR) improvement at the 10 MHz scrambling rate in simulation. For MKF, more significant tracking speed improvement exists for lower OSNR. MKF can be smoothly combined with an adaptive algorithm, which outperforms adaptive CKF throughout the simulations.展开更多
基金National Key Research and Development Program of China(2023YFB2805100)Natural Science Foundation of Guangdong Province(2023A1515110068)National Natural Science Foundation of China(62475296).
文摘In this paper,an efficient Ge_(25)Sb_(10)S_(65)(GeSbS)-loaded erbium-doped lithium niobate waveguide amplifier is demonstrated.By dimensional optimization of the waveguide,an internal net gain of approximately 28 dB and a maximum on-chip output power of 8.2 dBm are demonstrated upon 1480 nm bidirectional pumping.Due to the improved optical mode field distribution within the active erbium-doped lithium niobate film and the mode overlap ratio between the pump and signal sources,a 15% high conversion efficiency can be achieved at a modest pump power of 45 mW.Furthermore,the noise figure of the amplifier can be maintained below 6 dB for low-input-signal power levels.Compared to state-of-the-art erbium-doped waveguide amplifiers(EDWAs),this heterogeneously integrated device shows superior gain performance at the desired optical C-band while avoiding the complex plasma etching process of lithium niobate,providing an inspirative solution for power compensation in the optical telecommunications.
基金Zhaohui Li acknowledges the support of the National Basic Research Programme of China(973)(Project No.2012CB315603)National High Technology 863 Research and Development Program of China(Nos.2013AA013300 and 2013AA013403)+5 种基金the Research Fund for the Doctoral Program of Higher Education of China(20124401110003)National Natural Science Foundation of China(NSFC)(Grant No.61435006)the Program for New Century Excellent Talents in University(NCET-12-0679)in ChinaXuming Zhang acknowledges the NSFC(Grant No.61377068)the Hong Kong Research Grant Council(Grant Nos.PolyU 5327/11E and N_PolyU505/13)the Hong Kong Polytechnic University(Grant Nos.G-YN07,4-BCAL and G-YBBE).
文摘Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises among resolution,speed,and accuracy.Optical frequency combs are widely used for metrology of discrete atomic and molecular spectral lines.However,they are usually generated by optical methods and have large comb spacing,which limits the resolution for direct sampling of continuous spectra.To overcome these problems,this paper presents an original method to digitally generate an ultrafine optical frequency comb(UFOFC)as the frequency ruler for spectral measurements.Each comb line provides one sampling point,and the full spectrum can be captured at the same time using coherent detection.For an experimental demonstration,we adopted the inverse fast Fourier transform to generate a UFOFC with a comb spacing of 1.46 MHz over a 10-GHz range and demonstrated its functions using a Mach–Zehnder refractive index sensor.The UFOFC obtains a spectral resolution of 0.01 pm and response time of 0.7 μs;both represent 100-fold improvements over the state of the art and could be further enhanced by several orders of magnitude.The UFOFC presented here could facilitate new label-free sensor applications that require both high resolution and fast speed,such as measuring binding kinetics and single-molecule dynamics.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61420106011,61871408,and 61871082)
文摘We propose the modified Kalman filter(MKF) using the received signal for observation and constructing an inverse process of the conventional Kalman filter(CKF) for polarization de-multiplexing in coherent optical(CO) orthogonal frequency-division multiplexing(OFDM) transmissions. The MKF can avoid the convergence error problem in CKF without matrix inverse operation and has a faster converging speed and a much larger tolerance to the process and measurement noise covariance, about two orders of magnitude more than those of CKF. We experimentally demonstrate the 12 Gbaud OFDM signal transmission over 480 km standard singlemode fiber. The performance of MKF and CKF outperforms pilot-aided polarization de-multiplexing with better accuracy and nonlinearity tolerance.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFB1801704)National Natural Science Foundation of China(NSFC)(Nos.61871082 and 61871408)+2 种基金State Key Laboratory of Advanced Optical Communication Systems and Networks,Shanghai Jiao Tong University(No.2020GZKF014)Fundamental Research Funds for the Central Universities(Nos.ZYGX2020ZB043 and ZYGX2019J008)Open Fund of IPOC(BUPT)(No.IPOC2020A011)。
文摘Kalman filtering(KF) has good potential in fast rotation of state of polarization(RSOP) tracking. Different measurement equations cause the diverse RSOP tracking performances. We compare the conventional KF(CKF) and the modified KF(MKF), which have different measurement equations. Semi-theoretical analysis indicates the lower conditional variances of measurement residuals and process noise of MKF. Compared with CKF, the MKF has > 3 d B optical signal-to-noise ratio(OSNR) improvement at the 10 MHz scrambling rate in simulation. For MKF, more significant tracking speed improvement exists for lower OSNR. MKF can be smoothly combined with an adaptive algorithm, which outperforms adaptive CKF throughout the simulations.
