Rsearch On High Power Amplifier Similariton Mode-lock Laser Oscillator Based On Large Mode Area Photonic Crystal Fiber

Since the advent of first fiber laser in 1964,benefited from the ever maturing of the fabrication of fibers over the next few decades,laser based on fibers has developed so fast,especially the large mode area photonic crystal fiber,which owns unique advantages on supporting high power or high energy ultrashort pulses.Moreover,the advantages of compact size,easy-to-operation and high stability make it useful in so many applications,and as well,intriguing for most researchers.Based on the new dynamic regime of similariton evolution in the cavity,and taking advantages of the photonic crystal fiber,we demonstrated a high power amplifier similariton mode-locked laser.The theory research and numerical simulation of the amplifier similariton evolution provide a powerful prediction of the experiment.Finally,an output of multi-watt average power,with single pulse energy up to 69 nJ,and pulse width as short as 84 fs is achieved.The main work consists of this article as follows:1.An introduction of ultrashort pulse and the development of fiber mode-locked laser,especially the development of similariton mode-locked lasers.2.Introductions of the theory models about the propagation of pulse in fibers and the derivation of similariton solution.The characteristics of amplifier similariton are presented using theory models.The numerical simulation was built to explain the propagation of similariton pulse in the fiber with Schrodinger Equation.The effect of grating as a narrow bandwidth filter is analyzed with ABCDGF transformation matrix.It provides theory prediction for later experimental research.3.A new kind of high power amplifier similariton mode-locked laser was demonstrated with photonics crystal fiber.The laser is operated in the all-normal –dispersion region.It is based on nonlinear polarization rotation mode-locking and a narrow bandwidth grating filter with gauss shape for the purpose of pulse shaping.The laser directly outputs the similariton pulses as high as 5W average power at 72 MHz repetition rate with the pulse duration of 1.699 ps,corresponding to the pulse energy of 69 nJ.The dechirped pulse is 84 fs compressed by a pair of 1200 line/mm transmission gratings,which is near transform-limit.The experimental result shows a great match with the numerical prediction.To our knowledge,it is the highest average power ever reported based on amplifier similariton mode-locked laser with photonic crystal fiber in all-normal-dispersion region.The central wavelength can even be adjusted by the tuning the gratings.It's clear that the amplifier similariton with linear chirp can significantly suppress the wave-breaking effect while improving the output pulse energy,which is promising to achieve ultra-high power pulses with ultra-short pulse width.