Device and method for measuring half-wave voltage of electro-optic phase modulator

Abstract

The invention discloses a device and a method for measuring half-wave voltage of an electro-optic phase modulator. The device comprises a tunable laser device, a first optical coupler, a polarization controller, the electro-optic phase modulator to be detected, a second optical coupler, a photoelectric detector and a frequency spectrum analyzer which are connected in sequence and further comprises a microwave signal source and an acousto-optic frequency shifter. The device outputs optical carrier waves through the tunable laser device, divides the optical carrier waves into two beams through the first optical coupler, respectively processes the beams through the photoelectric detector and the electro-optic phase modulator to be detected, then combines the beams through the second optical coupler, achieves stable beat frequency, obtains the half-wave voltage of the electro-optic phase modulator by comparing the carrier wave beat frequency amplitude and the sideband beat frequency amplitude and has the advantages of high in resolution ratio, high in precision, good in accuracy, simple in structure and convenient to operate.

Description

[0001] technical field [0002] The invention relates to the field of optoelectronic technology, in particular to the field of optical fiber communication technology and photoelectric signal processing technology, in particular to a device and method for measuring the half-wave voltage of an electro-optic phase modulator. Background technique [0003] With the development of digital optical communication, the electro-optic modulator plays an important role in the theoretical research and practical application of signal processing in optical communication. The electro-optical phase modulator is one of the basic devices in optical transmission and optical signal processing systems. With the development of optical fiber communication systems becoming more and more mature, it is more and more important to accurately measure the characteristic parameters of the electro-optic phase modulator at each modulation frequency. , the half-wave voltage is one of the characteristic para...

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Problems solved by technology

[0004] At present, there are methods for measuring the half-wave voltage of electro-optic phase modulators: spectral analysis (Y. Shi, L. Yan and A. E. Willner. High-speed electrooptic modulator characterization using optical spectrum analysis[J]. Journal of Lightwave Technology , 2003, 21(10): 2358-2367.), FM-IM conversion method (S. J. Zhang, X. X. Zhang, Y. Liu. Swept frequency measurement of electrochemical phase modulators using dispersive fibers[J]. Chinese Physics Letters , 2012, 29(8):84217-84219.) and optical heterodyne method (R. E. Tench, J.-M. P. Delavaux, L. D. Tzeng, R. W. Smith, L. L. Buhl and R. C. Alferness. Performance evaluation of waveguide phase modulators for coherent systems at 1.3 and 1.5μm[J]. Journal of Lightwave Technology, 1987, 5(4):459-501.), wherein, the resolution of the spectroscopic analysis method is limited by the resolution of the spectrometer, and the resolution of the currently commercial spectrometer is 0.01nm, the corresponding frequency resolution is about 1.25GHz, which causes the difficulties of low frequency resolution, few measurable frequency points, low measurement accuracy, and high cost of measuring instruments; the FM-IM conversion method uses the fiber dispersion effect The phase modulation signal is converted into an intensity modulation signal, and the half-wave voltage of the electro-optic phase modulator is measured by a spectrum analyzer, which improves the measurement accuracy. Since the cumulative effect of dispersion is proportional to the square of the modulation frequency, in the low frequency band, the phase caused by the dispersion effect The conversion from modulation to intensity modulation is not obvious, which makes the signal-to-noise ratio of the low-frequency signal poor and affects the measurement accuracy; when measuring the half-wave voltage of the electro-optic phase modulator using the spectrum analysis method combined with optical heterodyne, in order to accurately measure the half-wave voltage of the electro-optical phase modulator The voltage and avoid phase modulation signals cannot be detected on the photodetector, and the use of dual lasers and complex beating frequency methods makes the measurement system relatively complex and unstable, which does not achieve the purpose of accurately measuring the half-wave voltage of the electro-optic phase modulator, and still exists many technical difficulties

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