Time-reversed optical parametric oscillation

In recent works, the idea of time-reversed laser oscillation has been proposed and demonstrated to realize a two-channel coherent perfect absorber [Y.?D. Chong et al., Phys. Rev. Lett. 105, 053901 (2010); W. Wan et al., Science 331, 889 (2011)]. Here the time reversal of optical parametric oscillation in a nonlinear χ(2) medium is considered and shown to realize a coherent perfect absorber for colored incident signal and idler fields. A detailed analysis is presented for the time-reversed process of mirrorless optical parametric oscillation in the full nonlinear regime.     

Optical parametric oscillation in RDA

Optical parametric oscillation has been observed in a crystal of rubidium dihydrogen arsenate (RDA) which was pumped by the second harmonic of a Q-switched ruby laser. The oscillator has a potential tuning range of 575 nm to 875 nm. The efficiency of the present oscillator is limited by the damage threshold of the mirrors at the ruby harmonic wavelength.     

Mirrorless parametric oscillation in BaTiO3

We report on the first observation of mirrorless oscillation in BaTiO₃ pumped by two nearly counterpropagating mutually incoherent light waves, both containing an ordinary and an extraordinary component. The oscillation waves appear at a certain angle defined by the phase matching condition for four-wave mixing of orthogonally polarized waves.     

Optical parametric oscillation in quasi-phase-matched GaAs

We demonstrate an optical parametric oscillator (OPO) based on GaAs. The OPO utilizes an all-epitaxially-grown orientation-patterned GaAs crystal that is 0.5 mm thick, 5 mm wide, and 11 mm long, with a domain reversal period of 61.2 microm. Tuning either the near-IR pump wavelength between 1.8 and 2 microm or the temperature of the GaAs crystal allows the mid-IR output to be tuned between 2.28 and 9.14 microm, which is limited only by the spectral range of the OPO mirrors. The pump threshold of the singly resonant OPO is 16 microJ for the 6-ns pump pulses, and the photon conversion slope efficiency reaches 54%. We also show experimentally the possibility of pump-polarization-independent frequency conversion in GaAs.     

Optical parametric oscillation in soliton-induced waveguides

We demonstrate experimentally an optical parametric oscillator constructed in a waveguide induced by a photorefractive spatial soliton and show that the pumping threshold is reduced considerably.     

Multiwave-pumped mirrorless parametric oscillation in BaTiO3

We report on the observation of mirrorless oscillation in photorefractive BaTiO₃ pumped by two pairs of two nearly counterpropagating light waves, each of them containing an ordinary and an extraordinary component of polarization. The oscillation waves are located on a cone with an apex angle defined by the phase-matching conditions of this process.     

Optical parametric oscillation in a vertical triple microcavity

We report the realization of a monolithic vertical-cavity, surface emitting micro-optical parametric conversion nanostructure, triply resonant with the parametric frequencies, allowing parametric oscillation with ultra-low pump power threshold. The photonic phase-space naturally provides triple resonance for the parametric frequencies, together with built-in cavity phase matching for the pump wave at normal incidence. Parametric oscillation is observed in both the strong and weak exciton–photon coupling regime, allowing high operating temperature. Signal and idler beams can be collected at 0 or at finite angles. The OPO threshold is low enough to envisage the realization of an all-semiconductor electrically-pumped micro-parametric oscillator.     

Model for multiwave-pumped parametric oscillation in BaTiO3

3 crystal subjected to two counterpropagating pairs of pump beams. The model explains the characteristic features of the above effect and predicts a number of new peculiarities that we have found in additional experiments. Received: 19 March 1997/Revised version: 9 June 1997     

Pure and mixed states in degenerate parametric oscillation

The degree of purity of the quantum state of electromagnetic field at the output of a degenerate optical parametric oscillator is theoretically analyzed. It is shown that, in the subthreshold and significantly suprathreshold modes, the degree of purity of the state of pairs of waves with frequencies ω _s ± Ω (ω _s is the signal mode frequency) is unity. Based on this fact, it is concluded that these pairs of waves parametrically develop independent of any other such pairs. At the same time, in the suprathreshold mode near the oscillation threshold, the degree of purity of wave pairs can be much smaller than unity. However, consideration of a tetrad of waves with frequencies ω _s ± Ω and ω _p ± Ω shows that this system is in a pure state, which indicates its independent development.     

Self-optical parametric oscillation in periodically poled neodymium-doped lithium niobate

Self-optical parametric oscillation is demonstrated for the first time to our knowledge in a periodically poled neodymium-doped lithium niobate (Nd:PPLN) crystal. The crystal is pumped by a cw Ti:sapphire laser at 813.5 nm. The Nd(3+) ions absorb the 813.5-nm radiation to generate 1084-nm laser oscillation. The internally Q switched 1084-nm radiation pumps the periodically poled lithium niobate host matrix to generate optical parametric oscillation at 1.55 and 3.6 microm . Up to 24% conversion efficiency from laser to signal is observed.     

Beam divergence effects on high power optical parametric oscillation

The beam divergence effects of the input pump laser on a high power nanosecond optical parametric oscillator （OPO） have been numerically simulated. The OPO conversion efficiency is affected due to the angular deviation of real laser beams from ideal phase matching conditions. Our theoretical model is based on the decomposition of the Gaussian beam and assumes each component has a single deviation angle and thus a particular wave vector mismatch. We take into account the variable intensity profile in the spatial and temporal domains of the Gaussian beam, the pump depletion effects for large-signal processes as well as the oscillatory effects of the three waves. Two nonlinear crystals β-BaB2O4 （BBO） and LiB305 （LBO） have been investigated in detail. The results indicate that the degree of beam divergence strongly influences the maximum pump intensity, optimum crystal length and OPO conversion efficiency. The impact of beam divergence is much more severe in the case of critical phase-matching for BBO than in the case of non-critical phase-matching for LBO. The results provide a way to choose the optimum parameters for a high power ns OPO such as the nonlinear material, the crystal length and the pump intensity, etc. Good agreement is obtained with our experimental results.     

Kerr-nonlinearity optical parametric oscillation in an ultrahigh-Q toroid microcavity

Kerr-nonlinearity induced optical parametric oscillation in a microcavity is reported for the first time. Geometrical control of toroid microcavities enables a transition from stimulated Raman to optical parametric-oscillation regimes. Optical parametric oscillation is observed at record low threshold levels (174 micro-Watts of launched power) more than 2 orders of magnitude lower than for optical-fiber-based optical parametric oscillation. In addition to their microscopic size (typically tens of microns), these oscillators are wafer based, exhibit high conversion efficiency (36%), and are operating in a highly ideal "two photon" emission regime, with near-unity (0.97+/-0.03) idler-to-signal ratio.     

一个新的秋千参激振动的数学模型

提出了一个新的秋千参激振动的数学模型,并根据此模型对秋千的参激振动现象作出了理论解释．     

温度调谐MgO：LiNbO3晶体光参量振荡器

采用调Q Nd:YAG激光倍频光(0.532μm)泵浦温度调谐MgO:LiNbO_3晶体单、双谐振光参量振荡器(OPO包括DRO、SRO)的实验结果.双谐振(DRO)调谐范围达844.1～1411.3nm,最低泵浦阈值0.22mJ/pulse;单谐振(SRO)调谐范围达738.9～1032.2nm,最低泵浦阈值0.66mJ/pulse.最大能量转换效率为10.4%.     

Photon conversion efficiency of backward travelling-wave parametric amplification and oscillation

Photon conversion efficiencies are expressed in terms of the jacobian elliptic function parameter η² and the overall gain. For amplifiers, the conversion efficiency is normally less than η², but their differences becomes small for gains larger than 5. Maximum efficiency equal to η² can only be achieved for oscillators.     

Four-wave parametric oscillation in sodium vapor by electromagnetically induced diffraction

We have observed a novel type of parametric oscillation in sodium atomic vapor where four off-axis signal waves simultaneously build up under resonant and counterpropagating pump beams with elliptical beam profiles. The four waves, two of them Stokes shifted and the other two anti-Stokes shifted, have similar output powers of up to 10 mW with a conversion efficiency of 30% and are parametrically coupled by electromagnetically induced diffraction.     

Singly resonant optical parametric oscillation in periodically poled lithium niobate waveguides

We report quasi-phase-matched singly resonant optical parametric oscillation in electric-field-poled lithium niobate waveguides. Parametric gains as high as 250%/W, an oscillation threshold of 1.6 W (peak), idler output powers of 220 mW, and a tuning range of 1180-2080 nm for pump wavelengths of 756-772 nm have been observed. Pump depletion is limited to 40% because of the multiple launched transverse modes at the pump wavelength. We predict that fully optimized waveguide singly resonant oscillators can have thresholds of ~100 mW, accessible to cw diode pumping.     

级联参量振荡产生太赫兹辐射的理论研究

针对光学参量振荡产生太赫兹波转换效率低的缺点, 提出了级联参量振荡产生太赫兹波的新机理以提高转换效率. 以周期极化铌酸锂晶体为例, 对级联参量振荡产生太赫兹波的原理和过程进行了理论研究. 分析了抽运光波长、周期极化铌酸锂晶体极化周期和工作温度对产生一阶、二阶闲频光频率的影响. 推导了三波共线相互作用条件下太赫兹波的增益特性和吸收特性. 计算结果表明, 通过级联参量振荡可以有效提高太赫兹波的转换效率, 并可以得到宽调谐的太赫兹波输出. 基于分析结果, 设计了周期极化铌酸锂晶体级联参量振荡产生高效率、宽调谐、窄线宽、连续太赫兹波的实验. 关键词： 太赫兹波 太赫兹波参量振荡 级联参量振荡