Efficient all-solid-state mid-infrared optical parametric oscillator based on resonantly pumped 1645 μm Er:YAG laser

Abstract

We first report an all-solid-state tunable mid-infrared singly resonant optical parametric oscillator based on a 1532 nm laser diode resonantly pumped, Q-switched 1.645 μm Er:YAG laser. An MgO-doped periodically poled lithium niobate was used as the nonlinear material. At the pulse repetition frequency of 2 KHz, a maximum overall average output power of 0.95 W with pump power of 2.8 W was achieved, corresponding to a conversion efficiency of 34% and a slope efficiency of 38%. The temperature tuning was performed giving signal and idler ranges of 2.67 to 2.71 μm and 4.18 to 4.31 μm, respectively. © 2012 Optical Society of America OCIS codes: 140.3070, 140.3580, 140.3600, 190.4970. Tunable laser sources operating in the 3 to 5 μm midinfrared waveband are of interest for a wide variety of applications, such as laser radar, sensing and monitoring environment, and mid-IR countermeasures [1,2]. Since the first actual optical parametric oscillator (OPO) based on a LiNbO 3 crystal was designed by Giordmaine and Miller in 1965 [3], the OPO through optical parametric conversion became one of the most important ways of getting tunable coherent light. Especially since the OPO using quasi-phase-matched technique was successfully demonstrated by Myers [4], it has become one of the most effective methods to get an ∼3-5 μm tunable laser where the conventional lasers perform poorly or are unavailable. In past decades, periodically poled LiNbO 3 (PPLN) has emerged as an excellent source of nonlinear frequency conversion. Using PPLN for QPM, various OPOs have been successfully demonstrated pumped by around 1 μm lasers and also achieved good results [5][6][7]. However, the pump-idler conversion efficiency was confined, not exceeding the quantum limit that is set by the Manley-Rowe relations. Alternatively, a few authors took insight in utilizing 2 μm lasers as the pump sources [8,9], in which the quantum conversion efficiency to mid-IR wavelengths is greater than with around 1 μm ones, but the conversion efficiency was still not greatly improved. Because the fluorescence linewidth of 2 μm laser crystals is rather broad [10,11], it is difficult to provide an ideal narrower linewidth 2 μm pump source for the OPO. To our knowledge, the highest conversion efficiency of the 2 μm pumping PPLN was 31% so far [12]. Additionally, 2 μm laser sources employed in the OPO systems were usually pumped by around a 790 nm laser diode (LD); hence the quantum conversion efficiency for the whole OPO systems are considerable limited. Recently, a few mid-IR OPOs pumped by erbium-doped fiber laser (EDFL) [13][14][15] or EDFL-pumped Er:YAG lasers [16] have been developed with quasi-phase matching. These methods provided a new pump source for the mid-IR OPOs, while the fiber laser itself adds complexity and volume to an OPO system. The quantum conversion efficiency for the whole system is also limited by the 980 nm LD used as the pump source of EDFL. The mid-IR OPOs based on 1.5 μm LD resonantly pumped Er:YAG laser have relatively high quantum conversi...

Passively Q-switched 1617-nm polycrystalline ceramic Er:YAG laser using a Cr:ZnSe saturable absorber

“…Eye-safe Q-switched Er-doped solid-state lasers operating at around 1.6 μm have lots of applications in remote sensing, ranging and free-space communications and can generate 3-to 5-μm mid-infrared waveband output via nonlinear frequency conversion [1,2]. For free absorption of the * Xiaoqi Zhang skcheung@siom.ac.cn 1 of a few tens of nanoseconds, a better alternative saturable absorber is Cr 2+ :ZnSe characterized by a large cross section (1.9 × 10 −18 cm 2 ), a long relaxation lifetime (8 μs) and absence of the excited-state absorption.…”

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methane in the atmosphere, the 1617-nm transition is more promising for applications which need long-distance propagation in free space than the 1645-nm transition [2,3].YAG crystal is used as the most common laser gain host because of its unique thermomechanical properties. Er:YAG crystal lasers have been demonstrated both in continuous-wave and Q-switched modes [1][2][3][4][5].

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“…Er:YAG crystal lasers have been demonstrated both in continuous-wave and Q-switched modes [1][2][3][4][5]. In 2007, a single-crystal Er:YAG which yielded a continuous-wave (CW) output power of 31 W was demonstrated at 1617 nm with a slope efficiency of 47 % with respect to incident pump power [3].…”

“…methane in the atmosphere, the 1617-nm transition is more promising for applications which need long-distance propagation in free space than the 1645-nm transition [2,3].…”

Topological Insulator: <formula formulatype="inline"><tex Notation="TeX">$\hbox{Bi}_{2}\hbox{Te}_{3}$ </tex></formula> Saturable Absorber for the Passive Q-Switching Operation of an in-Band Pumped 1645-nm Er:YAG Ceramic Laser

“…In order to realize the laser emission at this interested wavelength, the in-band pumping of Er:YAG crystal bulk lasers by direct diode at 1470 or 1532 nm, or, alternatively, a hybrid fiber-bulk laser configuration were commonly employed [4]. To establish the Q-switching (Q-S) operation at 1.645 m, the laser cavity must be incorporated with an intensity modulation component, namely, an electrooptic or an acoustic-optical switcher by Shen et al [5], Wang et al [6], and Moskalev et al [7], in which, however, the intensity modulation component shows the disadvantage of being expensive, lossy, and bulky. To overcome those drawbacks from those crystal-based modulators, Gao et al reported the first passive Q-S operation at 1.645 m with a single pulse energy of 7.05 J by a graphene saturable absorber [8].…”