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.     

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.     

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%.     

Mid-infrared generation based on a periodically poled LiNbO3 optical parametric oscillator

We report a nanosecond Nd:YVO_4-pumped optical parametric oscillator (OPO) based on periodically poled LiNbO_3 (PPLN). Tuning is achieved in this experiment by varying the temperature and period of the PPLN. The design of double-pass singly resonant oscillator (DSRO) and confocal cavity enables the OPO threshold to be lowered considerably, resulting in a simple, compact, all-solid-state configuration with the mid-infrared idler powers of up to 466mW at 3.41μm.     

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-peak-power, high-repetition-rate intracavity optical parametric oscillator at 1.57μm

We report a high-peak-power, high-repetition-rate diode-side-pumped Nd:YAG Q-switched intracavity optical parametric oscillator (IOPO) at 1.57μm with a type-Ⅱnon-critically phase-matched x-cut KTP crystal. The average power of 1.15 W at 1.57μm is obtained at 4.3-kHz repetition rate. The peak power of the pulses amounts to 33.4 kW with 8-ns duration. The average conversion efficiency from Q-switched 1.064-μm-wavelength input power to OPO signal output power is up to 10.5%.     

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.     

1.8 μm optical parametric oscillator based on KTiOPO4

A 1.8 ??m optical parametric oscillator pumped by a diode end-pumped acousto-optically Q-switched Nd:YAG is demonstrated. A 30-mm-long KTiOPO₄ crystal cut with an angle of ?? = 59.4°, ?? = 0° is employed as the OPO crystal. 685 mW signal laser at 1.8 ??m is obtained at the diode pump power of 13 W and the pulse repetition rate of 25 kHz. Simultaneously, 265 mW idler emission at 2.6 ??m is obtained. The corresponded diode-to-OPO conversion efficiency is 7.3%. The pulse width of the signal and idler wave are measured to be 4.5 and 2.5 ns, respectively. This gives a peak power of 6.1 and 4.2 kW, respectively.     

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.     

Tunable polarization-independent Šolc-type wavelength filter based on periodically poled lithium niobate

We demonstrated a compact structure to implement the tunable ?olc-type wavelength filter based on periodically poled lithium niobate device. The theoretical analysis and experimental results show that the wavelength filter exhibits polarization independent. By comparing the polarization-independent and single-pass ?olc-type filters, same wavelength spectrum response was observed, while the improvement on the transmission power was obviously achieved and the polarization dependent loss was eliminated efficiently using polarization diversity and multiplexing.     

Fiber parametric oscillator for the 2 μm wavelength range based on narrowband optical parametric amplification

We describe a widely tunable synchronously pumped coherent source based on the process of narrowband parametric amplification in a dispersion-shifted fiber. Using an experimental fiber with a zero-dispersion wavelength of 1590 nm and pump wavelengths of 1530 to 1570 nm yields oscillations at 1970 to 2140 nm-the longest reported wavelength for a fiber parametric oscillator. The long-wavelength oscillations are accompanied by simultaneous short-wavelength oscillations at 1200 to 1290 nm. The parametric gain is coupled to stimulated Raman scattering. For parametric oscillations close to the Raman gain peak, the two gain processes must be discriminated from each other. We devised two configurations that achieve this discrimination: one is based on the exploitation of the difference in group delay between the wavelengths where Raman and parametric gain peak, and the other uses intracavity polarization tuning.     

Efficient parametric conversion from 1.06 to 3.8 μm by an aperiodically poled cascaded lithium niobate

We experimentally demonstrated an efficient optical parametric oscillator (OPO) with high parametric conversion from 1.0645 to 3.8?μm. An aperiodically poled magnesium oxide doped lithium niobate wafer was designed and fabricated as the nonlinear crystal of the OPO. A linearly polarized acousto-optic Q-switched Nd:YVO4 laser was used as the pump source. High pump-to-idler conversion efficiency of 18.5% was achieved with a slope efficiency of up to 21.5%. When compared with a periodically poled channel fabricated on the same wafer, under the condition of output coupler optimized for the periodically poled lithium niobate based OPO, an improvement of slope efficiency by 28.3% from 15.2% to 19.5% and total efficiency by 12.5% from 13.6% to 15.3% under the highest pump power of 11?W was realized for the pump-to-idler conversion.     

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.     

Electro-optic tuning of a periodically poled LiNbO3 optical parametric oscillator and mixing its output waves to generate mid-IR tunable from 9.4 to 10.5 μm

We demonstrate electro-optic spectral tuning in a pulsed periodically poled LiNbO₃ (PPLN) optical parametric oscillator (OPO) in ns regime. A 3-cm-long LiNbO₃ crystal is segmented in three equal sections; the outer sections are periodically poled. The center segment is of single domain whose refractive index is changed by electro-optic effect. Applying voltage from 0 to −5000 V, the OPO signal and idler waves are tuned from 1.932 to 1.912 μm and 2.368 to 2.40 μm, respectively. The signal and idler waves obtained are difference-frequency-mixed in a 10 mm long AgGaS₂ crystal to produce mid-IR tunable from ∼10.5 to ∼9.4 μm, which matches the tuning range of a CO₂ laser.     

3–5 μm AgGaS2 optical parametric oscillator with prism cavity

Employing a coated right-angled sapphire prism as the OPO cavity mirror, AgGaS₂ type-I singly resonant optical parametric oscillator was demonstrated experimentally, which was pumped by a ns 1.064 μm Nd:YAG laser. Continuously tunable 2.35 to 5.27 μm radiation without changing cavity mirrors and maximum output energy 0.58 mJ per pulse are recorded.     

Efficient all-solid-state mid-infrared optical parametric oscillator based on resonantly pumped 1.645 μm Er:YAG laser

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.     

Mid-IR frequency comb source spanning 4.4-5.4 μm based on subharmonic GaAs optical parametric oscillator

Broadband mid-IR output suitable for producing 1000-nm-wide frequency combs centered at 4.9?μm was achieved in a degenerate subharmonic optical parametric oscillator (OPO) based on 500-μm-long Brewster-angled orientation-patterned GaAs crystal. The OPO was synchronously pumped at 182 MHz repetition rate by 100 fs pulses from a Cr2?:ZnSe laser with the central wavelength of 2.45?μm and the average power of 100 mW.     

Saturation spectroscopy of CO2 and frequency stabilization of an optical parametric oscillator at 2.77 μm

We report the frequency stabilization of a CW single-frequency, singly resonant optical parametric oscillator (OPO) to the saturation absorption center of the (12)C(16)O2[10°1,02°1](II)>←00°0 P(14) line at 2.77 μm. The CO2 molecules were excited by the OPO idler wave, and the absorption signal was monitored through the fluorescence at 4.3 μm using a gold-coated longitudinal cell. The idler frequency was stabilized onto the line center by wavelength modulation method. The linewidth of the saturation dip was estimated to be 4.7 MHz, and the achieved frequency stability was 3.9 kHz (3.6×10(-11)).     

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%.     

Compact and tunable mid-infrared source based on a 2 μm dual-wavelength KTiOPO4 intracavity optical parametric oscillator

Using a double resonant KTiOPO 4 (KTP) intracavity optical parametric oscillator operating at degenerated point of 2 μm,we demonstrate a unique mid-infrared source based on difference frequency generation in GaSe crystal.The output tuning range is 8.42-19.52 μm,and a peak power of 834 W for type-I phase matching scheme and 730 W for type-II phase matching scheme are achieved.Experimental results show that this oscillator is a good alternative to the generator of a compact and tabletop mid-infrared radiation with a widely tunable range.