In this study, the V-I transmission matrix formalism （V-I method） is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating （FBG）-based acousto--opfic modulators （UFBG-AOM）. The simu...In this study, the V-I transmission matrix formalism （V-I method） is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating （FBG）-based acousto--opfic modulators （UFBG-AOM）. The simulation results demon- strate that both the amplitude of the acoustically induced strain and the frequency of the acoustic wave （AW） have an effect on the spectrum. Additionally, the wavelength spacing between the primary reflectivity peak and the secondary reflectivity peak is proportional to the acoustic frequency with the ratio 0.1425 nm/MHz. Meanwhile, we compare the amount of calculation. For the FBG whose period is M, the calculation of the V-I method is 4 × （2M-l） in addition/subtraction, 8 × （2M - 1） in multiply/division and 2M in exponent arithmetic, which is almost a quarter of the multi-film method and transfer matrix （TM） method. The detailed analysis indicates that, compared with the conventional multi-film method and transfer matrix （TM） method, the V-I method is faster and less complex.展开更多
An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the sh...An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm.By using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.展开更多
A designed visual geometry group(VGG)-based convolutional neural network(CNN)model with small computational cost and high accuracy is utilized to monitor pulse amplitude modulation-based intensity modulation and direc...A designed visual geometry group(VGG)-based convolutional neural network(CNN)model with small computational cost and high accuracy is utilized to monitor pulse amplitude modulation-based intensity modulation and direct detection channel performance using eye diagram measurements.Experimental results show that the proposed technique can achieve a high accuracy in jointly monitoring modulation format,probabilistic shaping,roll-off factor,baud rate,optical signal-to-noise ratio,and chromatic dispersion.The designed VGG-based CNN model outperforms the other four traditional machine-learning methods in different scenarios.Furthermore,the multitask learning model combined with MobileNet CNN is designed to improve the flexibility of the network.Compared with the designed VGG-based CNN,the MobileNet-based MTL does not need to train all the classes,and it can simultaneously monitor single parameter or multiple parameters without sacrificing accuracy,indicating great potential in various monitoring scenarios.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61275076)
文摘In this study, the V-I transmission matrix formalism （V-I method） is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating （FBG）-based acousto--opfic modulators （UFBG-AOM）. The simulation results demon- strate that both the amplitude of the acoustically induced strain and the frequency of the acoustic wave （AW） have an effect on the spectrum. Additionally, the wavelength spacing between the primary reflectivity peak and the secondary reflectivity peak is proportional to the acoustic frequency with the ratio 0.1425 nm/MHz. Meanwhile, we compare the amount of calculation. For the FBG whose period is M, the calculation of the V-I method is 4 × （2M-l） in addition/subtraction, 8 × （2M - 1） in multiply/division and 2M in exponent arithmetic, which is almost a quarter of the multi-film method and transfer matrix （TM） method. The detailed analysis indicates that, compared with the conventional multi-film method and transfer matrix （TM） method, the V-I method is faster and less complex.
基金National Research Foundation of Korea(NRF)(2015R1A2A2A04006979,2015R1A2A2A11000907)Institute for Information and Communications Technology Promotion(IITP-2017-2015-0-00385)
文摘An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm.By using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.
基金supported by the National Key Research and Development Program of China (Grant No.2019YFB1803700)the Key Technologies Research and Development Program of Tianjin (Grant No.20YFZCGX00440).
文摘A designed visual geometry group(VGG)-based convolutional neural network(CNN)model with small computational cost and high accuracy is utilized to monitor pulse amplitude modulation-based intensity modulation and direct detection channel performance using eye diagram measurements.Experimental results show that the proposed technique can achieve a high accuracy in jointly monitoring modulation format,probabilistic shaping,roll-off factor,baud rate,optical signal-to-noise ratio,and chromatic dispersion.The designed VGG-based CNN model outperforms the other four traditional machine-learning methods in different scenarios.Furthermore,the multitask learning model combined with MobileNet CNN is designed to improve the flexibility of the network.Compared with the designed VGG-based CNN,the MobileNet-based MTL does not need to train all the classes,and it can simultaneously monitor single parameter or multiple parameters without sacrificing accuracy,indicating great potential in various monitoring scenarios.
