High spectral purity and tunable operation of a continuous singly resonant optical parametric oscillator emitting in the red

Continuous-wave oscillation of a singly resonant optical parametric oscillator operating from 619 to 640 nm has been obtained. Parametric gain is created in a MgO-doped periodically poled stoichiometric lithium tantalate crystal pumped at 532 nm. 100 mW of single-frequency red light have been generated. The signal frequency is tunable, and its frequency stabilization on an external reference has been achieved.     

Single-frequency quasi-continuous red radiation generated by a green-pumped singly resonant optical parametric oscillator

We demonstrate the operation of a quasi-continuous-wave optical parametric oscillator (OPO) in the red part of the visible spectrum by direct pumping from a frequency-doubled quasi-continuous-wave Nd:YAG laser. The OPO is singly resonant and based on a MgO-doped periodically poled stoichiometric lithium tantalate crystal. A single-frequency 1.2 W output power is obtained when an etalon is inserted inside the cavity.     

Fiber-laser-pumped continuous-wave singly resonant optical parametric oscillator

We report on what is to our knowledge the first continuous-wave (cw) optical parametric oscillator (OPO) that is pumped by a tunable fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled LiNbO(3) crystal in a four-mirror ring cavity. At a pump power of 8.3 W provided by the wavelength-tunable Yb-doped fiber laser, the singly resonant OPO generates 1.9 W of 3200-nm cw idler radiation. The singly resonant OPO was tuned from 1515 to 1633 nm (signal) and from 3057 to 3574 nm (idler) by means of the crystal temperature and poling period. We obtained a wide idler tuning range, from 2980 to 3700 mn, by tuning the wavelength of the fiber laser from 1032 to 1095 nm.     

Low-pump-threshold continuous-wave singly resonant optical parametric oscillator

We describe a compact all-solid-state continuous-wave singly resonant optical parametric oscillator (SRO) with a minimal pump-power requirement. The SRO is based on periodically poled LiNbO(3) as the nonlinear material and is pumped by a 1-W diode-pumped Nd:YVO(4) minilaser at 1.064 microm . By exploiting the intracavity pumping technique in a 50-mm crystal, we have achieved SRO operation threshold at a diode pump power of only 310 mW.At 1 W of input diode power, the SRO delivers 70 mW of output power in the nonresonant idler at 3.66 microm , at a photon conversion efficiency of 55%. Multiparameter tuning of the SRO yields a signal wavelength range from 1.45 to 1.60 microm and an idler wavelength range from 3.16 to 4.02 microm in the mid infrared. The device is characterized by robust turnkey operation and long-term amplitude-stable performance.     

基于光学参量振荡器的可调谐红外激光的强度噪声特性

红外激光光源在微量气体、高分辨率光谱分析和量子光学研究等领域具有重要的应用.本文利用锁定单共振光学参量振荡器内腔标准具的方案获得了无跳模连续调谐的红外激光输出,理论和实验研究了红外激光的强度噪声特性,分析了影响强度噪声的因素.通过控制非线性晶体的温度和标准具调制信号实现了对红外激光强度噪声的抑制.当控制非线性晶体工作温度为60℃,内腔标准具调制信号为8 kHz时,单共振光学参量振荡器输出信号光和闲置光的强度噪声分别降低了11和8 dB.     

Stable, continuously tunable operation of a diode-pumped doubly resonant optical parametric oscillator

We demonstrate, for what is the first time to our knowledge, long-term stable, continuously tunable operation of a doubly resonant optical parametric oscillator (OPO) pumped by a single-stripe diode laser without the use of an external semiconductor amplifier. The OPO is based on periodically poled lithium niobate and is pumped by a 150-mW distributed Bragg grating diode laser. 18-mW total output power is generated at 1.3- and 2.3-mum wavelengths. A cavity-length servo system allows continuous signal tuning of 17 GHz and idler tuning of 10 GHz, limited only by the range of a piezoelectric cavity mirror mount. OPO tuning is demonstrated from 1.1 to 1.4 mum and from 2.2 to 3.7 mum.     

Self-guided operation of singly resonant continuous-wave optical parametric oscillator based on bulk MgO-doped PPLN

We report on a self-guided operation of a green-pumped singly resonant continuous-wave optical parametric oscillator with a bulk MgO-doped PPLN crystal. It is achieved by increasing the OPO cavity length beyond the stability boundary so that the OPO can only oscillate with formation of a thermally induced waveguide inside the crystal. The effects of the thermal waveguide on the OPO performance are studied by measuring output power characteristics at different cavity lengths. Improvement of spatial mode quality and stability of output power by self-guiding is demonstrated. Measurement of temporal characteristics proves that formation of the waveguide originates from the photo-thermal effect in the nonlinear crystal by absorption of pump power.     

中红外连续波单谐振光学参量振荡器热致相位失配

为了研究热致相位失配对中红外连续波单谐振光学参量振荡器(CW-SRO)输出效率的影响, 结合CW-SRO计算模型和热传导方程,利用有限元分析方法,重点对输出3.3 m波长闲频光的CW-SRO进行了分析。计算了不同信号光输出耦合率及不同泵浦功率下CW-SRO晶体输出截面上热致相位失配量的分布。由计算结果可以看出：晶体吸收腔中振荡信号光是导致晶体热效应的主要因素;在相同的输入条件下,泵浦功率在30 W以上时CW-SRO的热致相位失配将会大大降低其泵浦损耗率;通过增加信号光输出耦合率的方法,可以减少热致相位失配对CW-SRO输出效率的影响,但CW-SRO的振荡阈值会增加。     

中红外连续波单谐振光学参量振荡器热致相位失配

为了研究热致相位失配对中红外连续波单谐振光学参量振荡器(CW-SRO)输出效率的影响, 结合CW-SRO计算模型和热传导方程,利用有限元分析方法,重点对输出3.3 m波长闲频光的CW-SRO进行了分析。计算了不同信号光输出耦合率及不同泵浦功率下CW-SRO晶体输出截面上热致相位失配量的分布。由计算结果可以看出:晶体吸收腔中振荡信号光是导致晶体热效应的主要因素;在相同的输入条件下,泵浦功率在30 W以上时CW-SRO的热致相位失配将会大大降低其泵浦损耗率;通过增加信号光输出耦合率的方法,可以减少热致相位失配对CW-SRO输出效率的影响,但CW-SRO的振荡阈值会增加。     

Theory of intracavity absorption spectroscopy with a singly resonant optical parametric oscillator

The suitability of a singly resonant optical parametric oscillator pumped by a one-mode field and oscillating simultaneously in several signal and idler modes, for intracavity absorption spectroscopic measurements is studied theoretically. For steadystate operation, the enhancement factor ξ indicating the increased detection sensitivity, is shown to be mainly determined by the ratio of the intensity in one of the signal modes to the intensity (per mode) due to parametric fluorescence. Hence, rather high values of ξ, say of order 10⁸ or more, might be attainable, at least in principle. For pulsed operation, on the other hand, a numerical analysis leads to the result that for realistic pulse durations only moderate values of ξ (smaller than some 10³) will be found. Paper given in parts at the 6th Vavilov-Conference on Nonlinear Optics, Novosibirsk, USSR, 1979.     

Focusing dependence of the efficiency of a singly resonant optical parametric oscillator

Received: 15 February 1998/Revised version: 6 April 1998     

Diode-pumped singly resonant continuous-wave optical parametric oscillator with wide continuous tuning of the near-infrared idler wave

We demonstrate wide, continuous tuning of the single-frequency idler wave of a cw singly resonant optical parametric oscillator (SRO). The SRO consists of a periodically poled LiNbO(3) crystal for quasi-phase matching in a four-mirror signal-resonant ring cavity. The SRO, excited by 2.25 W of 924-nm radiation from an InGaAs diode laser, generates as much as 200 mW of single-frequency 2.1-mum idler radiation. We tune the idler frequency continuously within a range as large as 56 GHz by changing the wavelength of the diode pump laser. The versatility of this continuously tunable single-frequency infrared source is demonstrated by recording of N(2)O rovibrational absorption lines near 2.1 mum.     

Cascaded continuous-wave singly resonant optical parametric oscillator pumped by a single-frequency fiber laser

We present a cascaded continuous-wave singly resonant optical parametric oscillator (SRO) delivering idler output in mid-IR and terahertz frequency range. The SRO was pumped by an ytterbium-doped fiber laser with 27 W linear polarization pump powers, and based on periodically poled MgO:LiNbO₃ crystal (PPMgLN) in two-mirror linear cavity. The PPMgLN is 50 mm long with 29.5 μm period. The idler power output at 3811 nm was obtained 2.6 W. The additional spectral components that have been attributed to cascaded optical parametric processes are described at increasing pump levels. Besides the initial signal component at about 1476.8 nm, further generated wavelengths with frequency shifts about 47 cm^?1, 94 cm^?1 and 104 cm^?1 were observed. It was speculated that the idler waves lie in the terahertz (THz) domain from the observed results.     

Continuous-wave, singly resonant, intracavity parametric oscillator

Performance characteristics of a continuous-wave intracavity optical parametric oscillator are described by use of an experimental arrangement comprising a KTP singly resonant oscillator located within a Ti:sapphire laser cavity and analyzed by use of a steady-state model. Internal and external powers, circulating fields, tuning ranges, spectral bandwidths, and amplitude-stability levels are measured and discussed. The nonresonant idler tunes from 2.53 to 2.87 microm, delivers a maximum output power of approximately 0.4W and displays long-term amplitude-stable operation. The total downconverted power approaches the optimum power coupled out of the Ti:sapphire laser in the absence of frequency conversion.     

500 GHz mode-hop-free idler tuning range with a frequency-stabilized singly resonant optical parametric oscillator

A 1064 nm pumped continuous-wave, mid-IR (3-4 μm), signal-wave resonant optical parametric oscillator is frequency stabilized at the kilohertz jitter level to the transmission peak of an external high-finesse Fabry-Perot cavity. Owing to the high stability of the resonator length against acoustical perturbation, fine pump tuning of the idler wave around 3.3 μm results in an unprecedented mode-hop-free continuous scan over 500 GHz (17 cm?1).     

Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator

We report the observation of thermal-induced optical guiding and bistability in a mid-IR cw, singly resonant optical parametric oscillator (SRO) at approximately 3.2 microm. The SRO employs a MgO:PPLN crystal as the gain medium and a 1-nm-linewidth Yb-fiber laser at 1.064 microm as the pump source. As soon as the pump power reaches the thermal guiding threshold at 16.5 W, the SRO shows a step increase in the parametric efficiency by a factor of 2.5. At 25 W pump power, the SRO generated 5.3 and 1.2 W at 1.58 and 3.23 microm, respectively, with single-longitudinal-mode performance for the 3.23 microm radiation.     

2.5-GHz repetition-rate singly resonant optical parametric oscillator synchronously pumped by a mode-locked diode oscillator amplifier system

We report on an optical parametric oscillator (OPO) that is synchronously pumped directly by a diode laser. This laser is an actively mode-locked master-oscillator power-amplifier system that produces 20-ps pulses at 927 nm with a repetition rate of 2.5 GHz and an average power of 0.9 W. The OPO, which is a singly resonant device based on periodically poled lithium niobate, generates 7.8-ps pulses. The OPO threshold is 300 mW of average pump power, and the maximum average idler output power is 78 mW at a wavelength of 2100 nm. By changing the crystal temperature we can wavelength tune the output in the ranges 1530-1737 nm (signal) and 1986-2348 nm (idler). Rapid wavelength tuning of the OPO over 46 nm (signal) and 74 nm (idler) is achieved through tuning the cavity length over 28 microm by use of a piezoelectric transducer.     

Solitons of singly resonant optical parametric oscillators

Single resonant parametric oscillators including intracavity quadratic and cubic nonlinearities are described in the mean-field limit with a cubic and quintic complex Ginzburg-Landau equation. Following our model, simple design criteria are derived for the generation of solitonlike pulses and beams for singly resonant optical parametric oscillators.     

Efficient continuous-wave eye-safe region signal output from intra-cavity singly resonant optical parametric oscillator

We report an efficient continuous-wave (CW) tunable intra-cavity singly resonant optical parametric oscillator based on the multi-period periodically poled lithium niobate and using a laser diode (LD) end-pumped CW 1064 nm Nd:YVO 4 laser as the pump source.A highly efficiency CW operation is realized through a careful cavity design for mode matching and thermal stability.The signal tuning range is 1401-1500 nm obtained by varying the domain period.The maximum output power of 2.2 W at 1500 nm is obtained with a 17.1 W 808 nm LD power and the corresponding conversion efficiency is 12.9%.