Singly-resonant Optical Parametric Oscillator Research Articles

Optimization of the resonant wave output coupling of a singly resonant optical parametric oscillator using an intracavity plate

We present a technique allowing us to optimize the output coupling of the resonant wave of a singly resonant optical parametric oscillator (SRO). By inserting a silica plate inside the cavity and tilting it around the Brewster angle, the output coupling of the SRO can be easily varied. This technique combines in principle the advantage of an efficient output coupling together with the possibility of controlling the frequency of the resonant wave of the SRO. We use this plate inside a 532-nm-pumped SRO to extract 1.6 W at 1.2 μm with a pump depletion of 80 %. We also show the possibility of determining the intracavity loss of the OPO, which is a useful parameter regarding its optimization.

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 27W linear polarization pump powers, and based on periodically poled MgO:LiNbO3 crystal (PPMgLN) in two-mirror linear cavity. The PPMgLN is 50mm long with 29.5μm period. The idler power output at 3811nm was obtained 2.6W. 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 1476.8nm, further generated wavelengths with frequency shifts about 47cm−1, 94cm−1 and 104cm−1 were observed. It was speculated that the idler waves lie in the terahertz (THz) domain from the observed results.

Adiabatic optical parametric oscillators: steady-state and dynamical behavior

We study singly-resonant optical parametric oscillators with chirped quasi-phasematching gratings as the gain medium, for which adiabatic optical parametric amplification has the potential to enhance conversion efficiency. This configuration, however, has a modulation instability which must be suppressed in order to yield narrowband output signal pulses. We show that high conversion efficiency can be achieved by using either a narrowband seed or a high-finesse intracavity etalon.

12 W mid-infrared output, singly resonant, continuous-wave optical parametric oscillator pumped by a Yb3+-doped fiber amplifier

We report a continuous-wave singly resonant optical parametric oscillator (SRO) with more than 12 W of idler power at 3414 nm when it was operated at 30°C. The SRO was directly pumped by a single-frequency, ytterbium-doped fiber laser with 49 W linear polarization pump powers, and based on 50 mm long periodically poled MgO:LiNbO3 crystal (PPMgLN) in two-mirror linear cavity with 30.5 μm grating period. It’s pump power at threshold was 5.4 W. The slope-efficiency and quantum-limited performance reached 26 and 79.2%, respectively. The beam polarization matched the e → e + e interaction in crystal. The idler waves were temperature tuned in the range of 3654 to 3811 nm and 3248 to 3414 nm based on two 50 mm long PPMgLN with 29.5 and 30.5 μm grating period. To the best of our knowledge, this is the highest continuouswave mid-IR output obtained for a fiber laser pumped optical parametric oscillator (OPO).

Real-time, subsecond, multicomponent breath analysis by Optical Parametric Oscillator based Off-Axis Integrated Cavity Output Spectroscopy

Breath analysis is an attractive field of research, due to its high potential for non-invasive medical diagnostics. Among others, laser-based absorption spectroscopy is an excellent method for the detection of gases in exhaled breath, because it can combine a high sensitivity with a good selectivity, and a high temporal resolution. Here, we use a fast-scanning continuous wave, singly-resonant Optical Parametric Oscillator (wavelength range between 3 and 4 μm, linewidth 40 MHz, output power > 1 W, scanning speed 100 THz/s) with Off-Axis Integrated Cavity Output Spectroscopy for rapid and sensitive trace gas detection. Real-time, low- ppbv detection of ethane is demonstrated in exhaled human breath during free exhalations. Also, simultaneous, real-time multi-component gas detection of ethane, methane and water was performed in exhaled breath using a wide spectral coverage over 17 cm(-1) in 1 second. Furthermore, real-time detection of acetone, a molecule with a wide absorption spectrum, was shown in exhaled breath, with a sub-second time resolution (0.4 s).

Low noise, continuous-wave single-frequency 1.5-μm laser generated by a singly resonant optical parametric oscillator

We report a low noise continuous-wave (CW) single-frequency 1.5-μm laser source obtained by a singly resonant optical parametric oscillator (SRO) based on periodically poled lithium niobate (PPLN). The SRO was pumped by a CW single-frequency Nd:YVO4 laser at 1.06 μm. The 1.02 W of CW single-frequency signal laser at 1.5 μm was obtained at pump power of 6 W. At the output power of around 0.75 W, the power stability was better than ±1.5% and no mode-hopping was observed in 30 min and frequency stability was better than 8.5 MHz in 1 min. The signal wavelength could be tuned from 1.57 to 1.59 μm by varying the PPLN temperature. The 1.5-μm laser exhibits low noise characteristics, the intensity noise of the laser reaches the shot noise limit (SNL) at an analysis frequency of 4 MHz and the phase noise is less than 1 dB above the SNL at analysis frequencies above 10 MHz.

Frequency-comb-referenced molecular spectroscopy in the mid-infrared region

A simple method for absolute-frequency measurements of molecular transitions in the mid-IR region is reported. The method is based on a cw singly resonant optical parametric oscillator (SRO), which is tunable from 3.2 to 3.45 μm. The mid-IR frequency of the SRO is referenced to an optical frequency comb through its pump and signal beams. Sub-Doppler spectroscopy and absolute-frequency measurement of the P(7) transition of the ν3 band of CH4 are demonstrated.

A continuous-wave tunable orange-red source based on sum-frequency generation in an intra-cavity periodicallypoled LiNbO3 singly resonant optical parametric oscillator cavity

This work demonstrates a tunable continuous-wave (CW) all-solid-stateorange-red source based on sum-frequency generation (SFG), using a tunable 1.4–1.5 µm signal and a 1064 nm pump of an intra-cavity periodically poledLiNbO3 optical parametricoscillator in a BBO (β-BaB2O4) crystal. Elaborate intra-cavity design ensured efficient CW singly resonant opticalparametric oscillator (SRO) operation. Intra-cavity SFG made full use of the highcirculating pump and signal power of the SRO under an external laser diode (LD) pumppower that was ten times higher than the SRO threshold. The output wavelength tuningrange was 605–623 nm. The maximum output power was 370 mW at 622.8 nmwith 17.1 W LD pump power, corresponding to an overall conversion efficiency of2.2%.

All fiber MOPA laser-pumped, continuous-wave, mid-infrared, singly-resonant optical parametric oscillator based on periodically poled MgO-Doped LiNbO3

We report a continuous-wave (CW) mid-infrared singly resonant optical parametric oscillator (SRO) based on periodically poled MgO-doped LiNbO3 (PPMgLN) pumped by a high power, single frequency fiber laser in master oscillator-power amplifier (MOPA) configuration at 1.064 μm. Using four-mirror ring OPO cavities, at the PPMgLN’s grating period of 30.5 μm and the temperature of 23°C, we achieved the maximum idler output power of 7.2 W at 3.4 μm when the pump power was 52.8 W. The total power-conversion efficiency from the pump to the idler in this experiment is about 13.6%, and corresponds to ∼44% of quantum-limited performance.

High efficiency and high beam quality 3.467-μm KTA extracavity optical parametric oscillator

An efficient single resonant extracavity optical parametric oscillator is demonstrated based on a Type II noncritical phase matching KTA crystal. Under a pump power of 0.6 W and a pulse width of 13 ns, the average power of 86 mW at 3.467 mu m is obtained with the pulse width of 6 ns and repetition rate of 100 Hz, corresponding to a conversion efficiency as high as 14% from 1.064 to 3.467 mu m. The beam spatial profile for 3.467 pm is near TEM(00) mode. The average power of 123 mW is also obtained with a multitransverse mode at the repetition rate of 200 Hz and an average power of 2.3 W of the pump laser. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2204-2207, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26247

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

Stable, high-power, second-harmonic-generation (SHG) of a compact CW Ytterbium (Yb) fiber laser at 1064 nm into the green and its use as a pump source for CW singly-resonant optical parametric oscillator (SRO) is demonstrated. Using a simple single-pass SHG configuration in MgO:sPPLT, as much as 9.6 W of single-frequency green radiation at 532 nm is generated from 30 W of fundamental power at a conversion efficiency of 32.7% in a Gaussian spatial profile with a beam quality factor of M2 < 1.3. Thermal effects have been investigated at different fundamental power levels and various thermal management schemes are employed to maximize the second-harmonic power. The green source is successfully deployed to pump a CW SRO tunable over 855–1408 nm, generating up to 2.1 W of idler at 1168 nm. The peak-to-peak idler power stability is better than 10.7% over 40 min, with beam quality factor M2 < 1.26 for the idler and M2 < 1.52 for the signal.

Stabilized diode laser pumped, idler-resonant cw optical parametric oscillator

We present a diode laser pumped continuous wave, pump-enhanced singly-resonant optical parametric oscillator (OPO). The cavity is stabilized by a Pound–Drever–Hall scheme using direct modulation of the diode laser. The system provides stable signal powers of up to 220 mW. The wavelength can be tuned between 1.40–1.60 μm for a ring or a linear cavity design by changing the crystal temperature. The relative fluctuations of the stabilized OPO’s wavelength are less than 10−7 for more than one hour. Using a self-heterodyne technique, we measure a linewidth of the signal wave of 3.5 MHz.

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 10kHz. When the pump power was 22.0W, a maximum idler output power of 3.4W at 3781.4nm was obtained. The thermal guiding effect caused by signal absorption was observed and the crystal heating power was measured with a new method.

High power, continuous wave, singly resonant OPO based on MgO:PPLN

A continuous wave (CW), extra-cavity singly resonant optical parametric oscillator (SRO) has been demonstrated. The SRO was based on 5% Magnesium-Oxide doped periodically-poled Lithium Nio-bate (MgO:PPLN) pumped by a Yb fiber laser centered at 1064.7 nm. The SRO was able to generate light with idler wavelengths ranging from 2.9 to 4.1 μm. For a pump power of 15 W, the idler output power varied from 7.54 W at 3.03 μm to 1.04 W at 4.05 μm. The oscillation thresholds were 2.0 W at idler wavelength 3.03 μm and 7.0 W at 4.05 μm.

Optimally-output-coupled, 17.5 W, fiber-laser-pumped continuous-wave optical parametric oscillator

We present a stable, high-power, fiber-laser-pumped, continuous-wave (cw), singly resonant optical parametric oscillator (SRO) for the mid-infrared in an output-coupled (OC) configuration, providing 17.5 W of total output power at 61% extraction efficiency. Using a single-frequency, cw Yb fiber laser at 1064 nm and a 50-mm-long MgO:PPLN crystal, through optimization of signal output coupling we generate up to 9.8 W of signal power in the near-infrared together with 7.7 W of idler power for 28.6 W of pump, while in the absence of output coupling, 8.6 W of idler power is generated for the same pump power at 30% efficiency. The SRO is tunable over 360 nm in the idler range. The deployment of signal output coupling results in a total tuning of 513 nm (120 nm of signal, 393 nm of idler) over which watt-level output power can be extracted. Through careful control of thermal effects we achieve a long-term peak-to-peak idler power stability of 5% over 14 hours near room temperature. The output beams have TEM00 spatial profile with M 2<1.28 for the idler and M 2<1.37 for the signal.

Continuous wave, singly resonant MgO:PPLN OPO pumped by a Nd:YVO4/YVO4 ring laser

A continuous wave (CW), extra-cavity singly resonant optical parametric oscillator (SRO) has been demonstrated. The SRO is based on 5% magnesium-oxide doped periodically-poled lithium niobate (MgO:PPLN) pumped by a CW Nd:YVO4/YVO4 ring laser centered at 1064.4 nm. The nonlinear crystal temperature is kept at 120.0 ± 0.1°C and a domain period of 30 μm is used in this experiment. When the pump power is 11 W, an output power of 2.0 W at the idler wavelength of 3.479 μm has been obtained from the OPO. The optical-optical conversion efficiency is about 18.2%, and the slope efficiency is about 20.8%.

One-Watt level mid-IR output, singly resonant, continuous-wave optical parametric oscillator pumped by a monolithic diode laser

We report more than 1.1 Watt of idler power at 3373 nm in a singly resonant optical parametric oscillator (SRO), directly pumped by a single-frequency monolithic tapered diode laser. The SRO is based on a periodically poled MgO:LiNbO3 crystal in a four mirror cavity and is excited by 8.05 W of 1062 nm radiation. The SRO pump power at threshold is 4 W. The internal slope-efficiency and conversion efficiency reach 89% and 44% respectively. The signal and idler waves are temperature tuned in the range of 1541 to 1600 nm and 3154 to 3415 nm respectively. To the best of our knowledge, this is the highest output obtained for a diode pumped optical parametric oscillator (OPO), and the first time a SRO is directly pumped by a monolithic tapered diode laser.

Frequency control of a 1163 nm singly resonant OPO based on MgO:PPLN

We report the realization of a singly resonant optical parametric oscillator (SRO) that is designed to provide narrow-bandwidth, continuously tunable radiation at a wavelength of 1163 nm for optical cooling of osmium ions. The SRO is based on periodically poled, magnesium-oxide-doped lithium niobate and pumped at 532 nm. The output coupling of the resonant idler wave is adjusted to yield up to 400 mW of 1163 nm radiation, with a bandwidth of a few megahertz. For continuous frequency tuning of the idler wave, the SRO is equipped with an intracavity etalon, and the cavity length is controlled with a piezo-actuated mirror synchronized to the etalon angle.

Nonlinear coefficient and temperature dependence of the refractive index of lithium niobate crystals in the terahertz regime

The effective nonlinear coefficient deff of lithium niobate is determined to be 94 pm/V for a process that converts infrared light to 1.35 THz radiation. This value is inferred from the performance of a continuous-wave, singly-resonant optical parametric oscillator, in which the cavity-enhanced signal wave of a primary parametric process acts as a pump wave for a cascaded process, generating terahertz waves. To quantify the nonlinear coefficient, the coupled wave equations including absorption are evaluated. Furthermore, from our measurements we also determine the temperature dependence of the refractive index to be dnTHz/dT=0.0013/K around 1.4 THz.

Broadband, high-power, continuous-wave, mid-infrared source using extended phase-matching bandwidth in MgO:PPLN

We report a compact and viable source of broadband, high-power, cw, mid-IR radiation based on a singly resonant optical parametric oscillator (SRO) pumped by a wide-bandwidth cw Yb fiber laser centered at 1060 nm. By exploiting the extended phase-matching bandwidth in a 50 mm crystal of MgO:PPLN and a ring SRO cavity, we obtain 5.3 W of broadband idler output for 25.5 W of pump at >80% depletion, transferring a pump bandwidth of 73.9 cm(-1) to an idler spectrum spread across an equal bandwidth centered at 3454 nm. By deploying output coupling of the signal, we generate 11.2 W of total power at 44% extraction efficiency with a pump depletion of >73% at the maximum available pump power. Measurements of transverse modal power confirm Gaussian distribution of signal and idler beams.