Frequency multiplication mode-locked laser based on micro-ring resonant cavity

Abstract

A frequency multiplication mode-locked laser based on a micro-ring resonant cavity comprises the components of a first wavelength division multiplexer, an Er-doped gain fiber, a second wavelength multiplexer, an optical isolator, a polarization controller, a four-port micro-ring resonant cavity, an output coupler and an optical delay line, wherein the first wavelength division multiplexer, the Er-doped gain fiber, the second wavelength multiplexer, the optical isolator, the polarization controller, the four-port micro-ring resonant cavity, the output coupler and the optical delay line are successively connected through an in-cavity single-mode optical fiber; wherein the input end of each of the two wavelength division multiplexer is provided with a pump light source. According to the frequency multiplication mode-locked laser, a repetition frequency can be adjusted in a manner that the free spectrum range of the micro-ring resonant cavity is used as a step length, thereby improving application flexibility and robustness of an existing mode-locked laser based on four-wave frequency mixing efficiency dissipation. The frequency multiplication mode-locked laser has wide application prospect at aspects such as ultrahigh-speed optical communication system, microwave photonics and optical analog-to-digital conversion in future. Particularly, the frequency multiplication mode-locked laser has particularly important application in the fields such as optical information processing and on-chip optical interconnection in which frequency multiplication optical clock signals are required.

Description

technical field [0001] The present invention relates to a mode-locked laser, in particular to an ultra-high repetition rate mode-locked laser based on the dissipative four-wave mixing effect, and more specifically to an ultra-high repetition rate mode-locked laser based on a microring resonator. And the pulse rate can be adjusted freely with the free spectral range of the intracavity microring resonator as the step size. Background technique [0002] Generally, high-speed optical pulse signals can be generated by mode-locked lasers and high-speed optoelectronics to adjust light waves. The latter solution is limited by the bandwidth of optical modulators and electrical signal generators. Currently, it can only reach tens of gigahertz, and its cost increases with the speed. The improvement has increased substantially. The mode-locked laser does not require high-frequency electronic devices, and has the advantages of simple structure, low cost, and high stability. It has extre...

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Problems solved by technology

[0003] Generally, the repetition frequency of fiber lasers is only a few megahertz to tens of megahertz, which is not conducive to its application in optical communication and other fields that require ultra-high repetition frequency pulses.

In order to increase the repetition frequency of fiber mode-locked lasers, there are several solutions: one is to shorten the cavity length of the laser and increase the mode interval of the laser cavity. Using this solution, an optical pulse with an ultra-high repetition frequency of 10 GHz can be obtained. However, Continuing to shorten the cavity length will not be able to obtain sufficient intracavity gain, so practical optical pulses cannot be generated, and its repetition frequency is locked with the determination of the laser cavity and cannot be adjusted

The second solution is a mode-locked laser based on the dissipative four-wave mixing effect. This type of laser can achieve a mode-locked pulse with a repetition frequency above THz, but it often has multiple longitudinal mode instabilities and cannot be practically applied. The frequency can be changed by adjusting the free spectral range of the intracavity filter, but it is difficult to achieve accurate frequency doubling of the rate

The third method is the method of harmonic mode-locking. The reported passive harmonic mode-locking can generate optical pulses of tens of gigahertz, and active harmonic mode-locking lasers can even generate optical pulses of hundreds of gigahertz. Wave-mode-locked lasers are susceptible to interference from different harmonic modes, resulting in time jitter and amplitude fluctuations. In addition, active mode-locked lasers are also limited by radio frequency signals, and the cost is high; this method can theoretically achieve frequency doubling of the pulse rate, but achieve ultra When the repetition frequency is high, its harmonic order is very high, which is difficult to realize in actual operation, and has extremely strict requirements on the control system

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