Compact, cost-effective and high power mid-infrared (MIR) optical parametric oscillator (OPO)

我们将演示一个低重复频率连续可调谐光学参量振荡器（OPO）工作在中红外（MIR）光谱区。OPO是类似于激光器的光源，也使用谐振器，但基于非线性晶体中的参数放大而不是受激发射的光学增益。OPO的主要吸引力在于信号和空闲波长可以在宽范围内变化。因此，可以访问MIR、远红外或太赫兹光谱区域中的波长。这使得OPO在生物医学、安全、国防和环境监测方面的潜在应用非常有价值。在环境监测方面，需要具有高壁插效率和小尺寸的坚固便携式MIR源，OPO可以提供这些。尽管它们具有惊人的功能，但由于其复杂性，OPO迄今为止还没有被广泛用作商业产品。社会和研究界可以从关于发展紧凑和强大的OPO的成功研究中获益。在我们与O/E-Land Inc.的合作项目中，我们的目标是开发一个紧凑和强大的OPO系统。更具体地，OPO的波长将通过在低精细腔内法布里-珀罗中平移扇出PPMgLN晶体来控制。OPO将由具有优良特性的主振荡功率放大器（MOPA）结构光纤激光器泵浦。从MOPA输出的泵浦脉冲将具有矩形形状，这在理论上被证明是改善OPO的性能，与高斯泵浦脉冲相比。MOPA的种子采用1064 nm波段增益开关激光二极管脉冲振荡器产生脉宽为250 ps ~ 1 ns的可调谐光脉冲。将在MOPA中引入无源光纤光栅来整形输入脉冲，以最大化MOPA的平均输出功率和效率。因此，预计MOPA的平均输出功率将加倍，从而在MIR中实现更高的平均功率。这种紧凑的MIR源将在制造业，生物医学，安全和国防等人类活动的各个部门中具有重要的应用。

We will demonstrate a low repetition rate continuously-tunable optical parametric oscillator (OPO) operating in the mid-infrared (MIR) spectral region. An OPO is a light source similar to a laser, also using a resonator, but based on optical gain from parametric amplification in a nonlinear crystal rather than from stimulated emission. A main attraction of OPOs is that the signal and idler wavelengths can be varied in wide ranges. Thus, it is possible to access wavelengths in the MIR, far-infrared or terahertz spectral region. This makes OPOs very valuable for potential applications in biomedical, security, defense, and environment monitoring. In terms of environmental monitoring, robust portable MIR sources with high wall-plug efficiencies and small dimensions are required, something that OPOs can offer. Despite their amazing capabilities, OPOs have so far not found widespread use as commercial products due their complexity. Society and research communities can reap the benefits of successful research studies on developing compact and robust OPOs. In our collaborative project with O/E-Land Inc., our goal is to develop a compact and robust OPO system. More specifically, the wavelength of the OPO will be controlled by translating a fan-out PPMgLN crystal in a low finesse intracavity Fabry-Perot. The OPO will be pumped by a master oscillator power amplifier (MOPA) structure fiber laser with excellent characteristics. The pump pulses from the MOPA will have a rectangular shape, which is theoretically proved to improve the OPO's performance, compared with the Gaussian pump pulse. The seed of MOPA generates tunable optical pulses from 250 ps to 1ns duration using a 1064 nm band gain-switched laser diode pulse oscillator. A passive FBG will be introduced in the MOPA to reshape the input pulse to maximize the average output power and efficiency of the MOPA. Consequently, it is expected that the MOPA's average output power will be doubled thus enabling more average power in the MIR. This compact MIR source will have important applications in various sectors of human activities from manufacturing, biomedical, security, and defence.