All-solid-state Lasers Technology Based On Nonlinear Frequency Conversion

All solid-state laser based on nonlinear optical frequency conversion technique is one of the hottest topics in the laser field and has achieved great progresses, owing to the advantages of compactness, stable output, high efficiency, and long lifetime. As we know, quasi-phase-matched (QPM) technique takes great part in the field of nonlinear frequency conversion. Besides, the sub-coherence-length micro-cavity can also compensate to the phase mismatching in the process of nonlinear frequency conversion with high efficiency, which is the so-called cavity phase matching (CPM). Based on the different types of phase matching methods and all-solid-state laser technique, a compact mode-locked lasers and mid-infrared laser are developed and a sub-coherent-length optical parametric oscillator consisting an MgO doped lithium niobate crystal is studied. The main results can be outlined as follows:1. The principle and development of the phase matching technology is introduced, including qusi-phase matching (QPM), multiple qusi-phase matching (MQPM) and cavity phase matching (CPM). The characteristics and types of phase matching are discussed to achieve different applications.2. We demonstrated nonlinear-mirror (NLM) mode-locked diode-pumped-solid-state (DPSS) Nd:YVO4laser operating respectively at1064nm and1342nm, where the NLM comprised a periodically-poled nonlinear crystal and a dichroic mirror. The self-starting thresholds for continuous-wave (CW) mode-locking were both below2W, which were significantly lower compared with saturable absorber mode-locking. The pulse width and the repetition rate of the mode-locked laser output were about10ps and100MHz respectively.3. We successfully fabricate a high efficiency mid-infrared laser source based on optical parametric oscillator (OPO) assisted by an intra-cavity optical parametric amplification (OPA). The OPA-assisted-OPO scheme was realized in one piece of commensurable dual-periodic superlattice in which the signal light generated from the OPO process serves as the pump light for the OPA process. The pump-to-idler conversion efficiency is17.8%and the slope efficiency is23.8%, and the enhancements of them are58.9%and67.6%respectively, comparing with the standard OPO scheme. Then a tandem periodically-poled MgO-doped stoichiometric lithium tantalate crystal is used to realize on-chip generation and amplification of mid-infrared radiation inside an OPO cavity. We achieved21.2%(or,24%slope efficiency) efficiency, which is the highest record for the pump-to-mid-infrared conversion to our knowledge, with1064nm Nd:YAG laser pump. The maximum average output power reached635mW under3.0W pumps.4. Cavity phase matching has been recently demonstrated as a phase matching method for efficient nonlinear frequency conversion in a microcavity. Here we extend it to the type I configuration using a sub-coherent-length optical parametric oscillator consisting an MgO doped lithium niobate crystal sheet. It generates tunable single-longitudinal-mode twin-beam, which covers cesium D2line of852.1nm and the Extended band of optical communication. This microcavity is capable of the peak output power of58kW with a maximum conversion efficiency of18.5%. Broad applications in the area of light-atom interaction, spectroscopy, optical telecommunication and quantum optics can be expected.