The Performance Of All-solid-state Mode-locked Lasers At1.3μm

Because of the excellent properties, such as ultra-short pulse duration, high repetition rate, broad spectrum and high peak intensity, ultrafast pulses have attracted much attention after the first ultrafast laser invented in1964. The widespread applications of the ultrafast lasers in the fields of science, industry, military, communication and medicine, have influenced and improved human society deeply. Mode-locking is an important technology to obtain the ultra-fast laser pulse. With the development of semiconductor technology, semiconductor saturable absorber mirror (SESAM) has been invented and used as a simple and efficient mode-locking component. The passively mode-locked lasers by incorporation of SESAMs have produced unsurpassed performance and become the hotspot of laser research. High power picosecond laser at1.3μm has attracted considerable attention in many fields, such as remote sensing, information storage, and atmospheric pollution monitoring. Such laser is also important for the efficient fiber communication because of the coincidence with the low-dispersive and low-loss spectrum of silica fiber. Moreover,1.3μm picosecond (ps) laser with high repetition rate and large energy is advantageous for medical treatment by considering the efficiency of vaporization and precise cutting soft biological tissues and blood coagulation, because the water molecules present a suitable optical absorption at this wavelength region.1.34μm laser pulses with large pulse energy and high repetition rate have great value for the spectral exploration of underground oil and gas. because of their coincidence with the absorption bands of some clay minerals that can characterize hydrocarbon micro-seepage. Compare with fast development of1.0μm mode-locked laser, LD pumped mode-locked operation in1.3μm have been seldom researched. In this paper, we do some theoretical and experimental study on diode-pumped passively mode-locked lasers at1.3μm by SESAM.1. We introduced the development history of all solid-state lasers, value of the research on1.3μm ultrafast lasers as well as current actuality in this field. 2. Based on the principle of mode-locking, we analyzed the mechanisms of mode-locking with SESAMs. The important parameters of SESAM which influence the output properties of mode-locked laser, such as structure, macroscopic properties, have been introduced and theoretically analyzing. The critical condition of continuous wave (CW) mode-locking was also analyzed.3. We have discussed the main factors which should be considered in the design of mode-locking cavity, and analyzed the influence on the SESAM mode-locked laser resulting from these factors. Based on the optimum cavity design, the stable SESAM CW mode-locked Nd:YVO4laser at1342nm has been realized. We investigated the conventional CW mode-locked Nd:YV04laser and CW mode-locked bonding YVO4/Nd:YVO4/YVO4laser, respectively. The maximum average output power of2.19W and2.97W were obtained, and the minimum pulse widths were8.6ps and9.96ps, respectively. YVO4/Nd:YVO4/YVO4crystal can serve as promising substitutes for a conventional Nd:YVO4crystal to reduce thermal lensing effect and scale to a higher average power of diode-end-pumped CW mode-locked Nd:YVO4lasers operated at1342nm. The maximum output power obtained from the YVO4/Nd:YVO4/YVO4mode-locked laser is increased by36%than the Nd:YVO4mode-locked laser with the same cavity.4. The LD-end-pumped1.3μm ps mode-locked lasers by using Nd-doped garnet crystals as gain medium were experimentally investigated. With Nd:YAG crystal, the diode-pumped passively mode-locked laser at1338nm by use of SESAM with watt-level output power was demonstrated. The performance of the passively CW mode-locked Nd:GGG laser at1331.3nm with a SESAM was investigated for the first time to our knowledge. The results shown that, Nd:GGG crystal is not only an excellent candidate of the solid state heat capacity laser, but also potentially suitable in diode-pumped mode-locked lasers. We have demonstrated a dual-wavelength synchronously mode-locked Nd:LGGG laser centered at1331.3nm and1336.4nm with a SESAM.