All-fiber Tune Q-switched Laser And The Laser Mode

Fiber laser, as a new subject, has been developing rapidly in recent years, especially the short pulse fiber laser. Because of its potential application in both optical soliton and optical time division multiplexing communication system in the future, it received more and more attention. In this paper, the author generalizes the latest development of Q-switch laser and introduces the common Q-switch. The author uses fiber M-Z interferometer as Q-switch, realize the fiber laser as all fiber device. We studied the active Q-switching, self-Q-switching, the wavelength tune and the mode structures. The main content is following:(1) In theory and practice, the Q-switch—fiber M-Z interferometer is researched, observed the interferometer spectrum of fiber M-Z interferometer, proving that fiber M-Z interferometer is a kind of comb filter.(2) Fiber M-Z interferometer driven by outside signal, laser put out stable Q-switched laser pulses, the output frequency can be tuned from 100Hz to 999Hz continuously, duty cycle is1:1000, peak power reach 1.2W, if properly decreasing free spectrum range of interferometer, the pulse-width can be further cut down from 4.2μs to 1μs.(3) Without driving signal, all fiber Q-switched lasers can achieve self Q-switched pulse, measuring the effect of different pumped power to self Q-switched and giving reasonable theory analysis.(4) Using Cantilever beam to tune fiber grating to achieve wavelength linear tuning of fiber laser, linear degree is 0.9997, get tuning range of 5.7nm, the width of laser is less than 0.1nm, out-put power is more than 1.2mw.(5) Studying mode structure of fiber laser by spherical surface scanning interferometer, in theory deducing the method of measuring width by spherical surface scanning interferometer, proposing two kind of narrow width fiber lasers.