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Method for locking LiNbO3 Mach-RPAMZM offset working point

A technology of biasing the operating point and modulator, which is applied in the field of optical fiber communication systems, can solve the problems of transmission signal influence and system security, and achieve the effect of improving the locking accuracy

Inactive Publication Date: 2013-08-21
TAIYUAN SHANDA YUGUANG TECHNOLOGICAL
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  • Abstract
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  • Application Information

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Problems solved by technology

At present, the feedback control method of low-frequency disturbance signal is often used in engineering to automatically control the bias point of the modulator [Journal of Lightwave Technology, 2010, vol.28, no.11, pp.1703-1706]. A low-frequency and small-amplitude disturbance signal is added to the bias. Its advantages are good stability and high locking accuracy. The disadvantage is that an additional disturbance signal needs to be added. However, in some application fields, such as in continuous variable quantum key distribution systems , this disturbance signal will affect the useful transmission signal, and then affect the security of the entire system

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  • Method for locking LiNbO3 Mach-RPAMZM offset working point
  • Method for locking LiNbO3 Mach-RPAMZM offset working point

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Embodiment Construction

[0027] figure 1 Shown is the method schematic diagram of the present invention, comprises laser 1, LiNbO 3 Mach-Zehnder modulator 2, beam splitter 3, photodetector 4, microprocessor 5. Use a beam splitter to extract a small part of the optical signal as a feedback signal and input it to the microprocessor.

[0028] The operation steps are as follows:

[0029] (1) Initialize the half-wave voltage V of the modulator π , the maximum output light intensity P in T D , the total measurement noise (with the maximum transmitted light intensity P in T D as the unit), where, is the electronic noise of the photodetector, is the detection noise caused by the laser power fluctuation, and C is the standard deviation of the light intensity fluctuation detected by the photodetector when the modulator is at its maximum pass. According to the formula (2), the bias phase θ caused by the test voltage can be obtained 0and the relationship between the locking accuracy Δθ of the bias op...

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Abstract

The invention provides a method for locking a LiNbO3 Mach-RPAMZM off set working point. When a modem is not provided with radio-frequency signals, proper detecting voltage is added at the offset input end. A photoelectricity detector is used for detecting light intensity at the output end of the modem. The light intensity is input to the microprocessor as feedback signals. The microprocessor can calculate voltage corresponding to any phase position on a transfer function of the modem at present. In order to reduce influence of laser power fluctuation on the feedback signals, largest output light intensity of the modem is calibrated with a certain period. According to the method, no extra disturbance signals need adding, no extra noise can be caused, and any phase position point can be locked. Through selection of the proper testing voltage, the feedback signals are enabled to be influenced to a minimum degree by system noise. Locking precision can be greatly improved. The method is simple in device, convenient to operate, and high in stability. Moreover, the laser power fluctuation and light path consumption influence the system little.

Description

technical field [0001] The invention relates to an optical fiber communication system, in particular to a locking LiNbO 3 A method for biasing the operating point of a Mach–Zehnder modulator. Background technique [0002] Driven by the exponential growth of network capacity and global integration, the optical fiber communication system is rapidly developing towards the direction of large capacity, high speed, and long-distance transmission. The performance and efficiency of the modulator first determine whether the optical fiber communication system can achieve this Target. LiNbO 3 The Mach-Zehnder modulator has the advantages of stable performance, low loss, high electro-optical efficiency, adjustable chirp, low driving voltage and large bandwidth, and has become the most widely used high-speed modulator in optical fiber communication systems. LiNbO 3 When the modulator is used, it is necessary to load a bias voltage to the modulator to ensure that its signal modulation...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02F1/035
Inventor 李永民王少锋王旭阳彭堃墀
Owner TAIYUAN SHANDA YUGUANG TECHNOLOGICAL
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