Period and temperature tuning of cascaded opticalparametric oscillator based on periodically poled LiNbO3

We report the broadly tunable source by a cascaded optical parametric oscillator in the periodically poled LiNbO_3 (PPLN) with domain grating period and temperature tuning. The optical parametric oscillator was pumped by a passive Q-switched Nd:YVO_4 laser. Multi-wavelength outputs from visible to infrared were obtained. The temperature of the PPLN crystal changed within the range of 70－150℃ with different periods of PPLN. The tunable range covered from 433 to 1657nm.     

Angle-tuned signal-resonated optical parametric oscillator based on periodically poled lithium niobate

We demonstrate an angle-tuned signal-resonated optical parametric oscillator (OPO) with periodically poled lithium niobate (PPLN) pumped by a diode-pumped Nd:YVO4 laser. 1499.8 - 1506.6 nm of signal wavelength is achieved at 140℃ by rotating a 29-μm period PPLN from 0° - 10.22° in the x-y plane while keeping the pump wave vertical to the resonator mirrors. Two pairs of the signal and idler waves of the same wavelengths can be achieved symmetrically for each pair of angles of rotation with same absolute value and opposite sign. Theoretical analyses on angle-tuned PPLN-OPO with pump wave vertical to the resonator mirrors are presented and in good agreement with our experimental results. It is also found that all interacting waves in the cavity (not inside the crystal) are always collineax for PPLN-OPO with the pump wave vertical to the resonator mirrors while phase-matching is noncollinear within the crystal.     

Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2-μm laser

We present a 3 5 μ m optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μ m laser. The tuning curves of ZGP OPO are calculated. The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7 4.6 μ m, is cut as θ =53.5°, φ =0°. When the pump power of 2.1-μ m polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μ m, respectively. Pulse duration is about 27 ns. Beam quality factor M 2 is better than 1.8. The tunability of 3 5 μ m can be achieved by changing the angle of the ZGP crystal.     

High efficiency double-pass-pumped 2 μm periodically poled MgO:LiNbO3 optical parametric oscillator

A high efficiency near-degenerate periodically poled MgO:LiNbO₃ optical parametric oscillator pumped by a nanosecond Nd:YVO₄ laser is demonstrated. Under a 1.064 ??m pump power of 7.2 W, an output power of 5.3 W with an optical-to-optical conversion efficiency of 74% and a slope efficiency of 82% in the 2 ??m region is obtained in a double-pass-pumped doubly resonant geometry at 20 kHz repetition rate.     

A periodically poled LiNbO3 in wavelength conversion optical parametric generator from 2 to 3.88 ——4.34 μm

A periodically poled lithium niobate （PPLN） optical parametric generator （OPG） pumped by a laser diode （LD）-pumped Q-switched Tm,Ho：GdVO4 laser operated at 2.048 μm with pump pulse of 25 ns and repetition rate of 10 kHz is reported. A continuous tunable middle-infrared （mid-IR） spectrum of 3.88 - 4.34 μm is obtained by changing the crystal temperature from 50 to 124℃. When the incident pump power is 3 W, the total OPG output power is 95 mW, corresponding to optical conversion efficiency of 3.2%.     

Generation of a squeezed state at 1.55 μm with periodically poled LiNbO3

We report on the generation of a squeezing vacuum at 1.55 μm using an optical parametric amplifier based on periodically poled LiNbO 3.Using three specifically designed narrow linewidth mode cleaners as the spatial mode and noise filter of the laser at 1.55 μm and 775 nm,the squeezed vacuum of up to 3.0 dB below the shot noise level at 1.55 μm is experimentally obtained.This system is compatible with standard telecommunication optical fibers,and will be useful for continuous variable long-distance quantum communication and distributed quantum computing.     

Low-Threshold Mid-Infrared Optical Parametric Oscillator Using Periodically Poled LiNbO33

We report the generation of tunable mid-infrared optical pulses using all-solid-state pumped optical parametri coscillator in a periodically poled lithium niobate. Several ways were used to lower the threshold, resulting in a mean threshold as low as 6.5mW and an achievement of wavelength conversion in the 2.77-4.04μm spectral range. Continuous tuning range from 2.97 to 3.25μm was achieved. The maximum idler output power of 466mW at the wavelength of 3.41μm was obtained, which represents an optical-to-optical conversion efficiency of 19% from incident pump power to the idler output.     

Widely and continuously tunable optical parametric generator based on MgO-doped periodically poled LiNbO_3 crystal

A widely and continuously tunable optical parametric generator (OPG) pumped by a 1064-nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on MgO-doped periodically poled LiNbO3 crystal with a multigrating structure (29.2-30.4μm) is reported. A broad continuous signal spectrum of 1513-1700 nm is obtained by changing the crystal grating periods from 29.2 to 30.4μm and by tuning the crystal temperature from 30 to 180℃simultaneously. When the average pump power is 1.82 W with pulse duration of about 70 ns operating at a repetition rate of 10 kHz, the maximum signal output power of the periodically poled MgO-doped lithium niobate (PPMgLN) OPG is about 210 mW corresponding to the idler and total powers of 118.4 and 328.4 mW respectively.     

Continuous-wave, single-frequency intracavity singly resonant optical parametric oscillator at 1.5-μm wavelength

We present a 1.5μm continuous-wave （CW） single-frequency intracavity singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO is placed inside the ring cavity of a single-frequency 1.06μm Nd：YVO4 laser pumped by a laser diode. The device delivers a maximum single-frequency output power of 310 mW at a resonant signal wavelength of 1.57 μm. The signal wave could be tuned from 1.57 to 1.59 μm by temperature tuning of PPLN crystal over the range of 130 - 170℃.     

LiNbO3电光调谐光学参变振荡器

在光学参变振荡器中 ,角度或温度调谐方式的最大缺陷就是参变光波长变化较慢 ,调谐操作复杂 ;电光调谐方式具有调谐速度快 ,操作简单的优点。利用非线性光学晶体LiNbO3 的电光效应 ,在 1 0 6 4 μmNd∶YAG激光器输出的抽运光作用下 ,切割角θ =4 7.5°,在垂直于 1.0 6 μm抽运光偏振方向上加 - 4 .5 +4.5kV直流电压 ,实现参变光波长调谐输出 ,输出光能量约为 2 6mJ左右 ,转换效率 η≈ 17.3%。实验所得的参变光波长变化与调谐电压的线性关系与理论计算相吻合 ,为实现光学参变振荡器的快速调谐快速输出提供了一种可行的技术途径。     

Low-threshold, high-efficiency, high-repetition-rate optical parametric generator based on periodically poled LiNbO3

We report a high-repetition-rate optical parametric generator (OPG) with a periodically poled lithium niobate (PPLN) crystal pumped by an acousto-optically Q-switched CW-diode-end-pumped Nd:YVO_4 laser. For the maximum 1064nm pump power of 970mW, the maximum conversion efficiency is 32.9% under the conditions of 250℃, 1064nm pulse repetition rate of 22.6kHz and pulse width of 12ns, and the PPLN OPG threshold in the collinear case is less than 23.7μJ. The output power increases with the increase of the crystal temperature. The 1485－1553nm signal wave and 3383－3754nm idler wave are obtained by changing the temperature and the angle of the PPLN crystal.     

High efficiency continuous-wave tunable signal output of an intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

In this paper we report on a continuous-wave (CW) intracavity singly resonant optical parametric oscillator (ICSRO) based on periodically poled LiNbO₃ (PPLN) pumped by a diode-end-pumped CW Nd:YVO₄ laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406~nm to 1513~nm is obtained. At a PPLN grating period of 29~μ m and a temperature of 413~K, a maximum signal output power of 820~mW at 1500~nm is achieved when the 808~nm pump power is 10.9~W, leading to an optical-to-optical conversion efficiency of 7.51%.     

Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.     

1-W, high-repetition-rate room temperature operation of mid-infrared optical parametric oscillator based on periodically poled MgO-doped LiNbO

In this paper a high-repetition-rate mid-infrared （mid-IR） optical parametric oscillator based on periodically poled MgO-doped LiNbO3 （PPMgLN） at room temperature was demonstrated. The maximum average mid-IR output power at 3.63μm was 1.02 W with the repetition rate of 60kHz and corresponding efficiency from the pump to the idler was 26.7%. The temperature tuning and the period tuning characteristics were also discussed.     

Widely tunable, high-repetition-rate, dual signal-wave optical parametric oscillator by using two periodically poled crystals

This paper reports on a high-repetition-rate dual signal-wave (DSW) optical parametric oscillator (OPO) operating at the 1.5 μm band with tunable wavelength intervals from 2.5 nm to 69.1 nm. Two periodically poled crystals, a periodically poled lithium niobate (PPLN) with multiple gratings and a single grating MgO-doped PPLN (PPMgOLN), are cascaded in the same OPO cavity to generate dual signal-waves by using quasi-phase-matched (QPM) technique. The pump source was a Q-switched diode-pumped Nd:YVO₄ laser operating at 50 kHz. At an incident pump power of 3 W, an average output power of 169.6 mW at 1489.2 nm and 1558.3 nm has been achieved.     

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:YVO₄ 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%.     

High repetition rate mid-infrared generation with singly resonant optical parametric oscillator using multi-grating periodically poled MgO:LiNbO3

A high repetition rate mid-infrared singly resonant optical parametric oscillator (OPO) using MgO-doped multi-grating periodically poled LiNbO₃ (MgO:PPLN) is demonstrated. A 1064 nm Q-switched Nd:YVO₄ laser at 10 kHz repetition rate and pulse width of 17.8 ns was used to pump the OPO. The period of the quasi-phase matched (QPM) grating in the multi-grating MgO:PPLN chip varied from 25.5 to 31.5 μm in steps of 0.5 μm. This corresponds to the generation of a signal beam from 1.37 to 1.64 μm and an idler beam from 3.0 to 4.8 μm, respectively. A maximum signal power of 250 mW and idler power of 140 mW has been obtained with an input pump beam of power 1.92 W, for a grating period of 30.5 μm. A maximum optic-optic conversion efficiency of 20% and 7.4% in the idler has been observed. It has been observed that the output power increases as the period of the grating increases.     

准相位匹配PPMgLN光参量振荡技术

 理论上分析了PPMgLN光参量振荡波长调谐特性,计算了泵浦阈值和转换效率。准相位匹配情况下,周期调谐是获得中红外波长调谐有效方法之一。采用高斯光束泵浦,当泵浦功率密度超过阈值泵浦功率密度约6.5倍时,可以获得最高转换效率,约71%。采用1 064 nm激光泵浦多周期PPMgLN晶体,实验上获得了波长调谐范围2.7~4.8 mm,当泵浦功率为8 W时,在波长3.7 mm处激光输出功率超过1.6 W,斜效率超过20%,相应的转换效率约为69%,与理论分析基本一致。     

High-power, high-repetition-rate mid-infrared generation with PE-SRO based on a fan-out periodically poled MgO-doped lithium niobate

We present a high-average-power, pulsed mid-infrared pump-enhanced singly-resonant optical parametric oscillator (PE-SRO) using a fan-out periodically poled MgO-doped lithium niobate (MgO:PPLN). The pump laser is a Q-switched Nd:YAG laser with a repetition rate of 10 kHz. When the pump power was 22.0 W, a maximum idler output power of 3.4 W at 3781.4 nm was obtained. The thermal guiding effect caused by signal absorption was observed and the crystal heating power was measured with a new method.