Parametric Oscillator Research Articles

Production of entangled photon pairs is important in secure communication systems, quantum computing, and fundamental physics experiments. Achieving efficient generation of such photon pairs with low-loss parametric oscillators is a key objective in advancing integrated quantum technologies. However, spatially separating the generated photons while preserving their entanglement represents a significant technical challenge. In this work, we demonstrate nonlinear generation of correlated optical harmonics based on non-degenerate four-wave mixing with an optimally pumped optical microcavity with Kerr nonlinearity. The phase matching of the process is achieved with self-injection locked lasers producing parametric oscillation while locked to two different modes of the microresonator. This condition is reminiscent of slow-light technique developed for coherent atomic systems. The experimental design, utilizing counterpropagating light from two self-injection locked lasers, also effectively addresses the challenge of spatial separation of the generated harmonics. Additionally, we demonstrate correlation mediated by self injection locking and Kerr nonlinearity between the two lasers. We validate the theoretical predictions using two self-injection locked semiconductor lasers integrated with a crystalline whispering gallery mode resonator with optimized spectral structure. ©2025 All Rights Reserved.

Short-Pulse 2 μm optical parametric oscillator based on stimulated Brillouin scattering technology

A computationally efficient analytical modeling approach for parametric oscillations in floating bodies

We present results for novel design and implementation of a high-power, high-resolution continuous-wave optical parametric oscillator (OPO) emitting mid-infrared radiation tunable from 3-4 μm, with output powers in excess of 2.5 W. Our home-built "JILA OPO" design is based on a periodically poled lithium niobate fanout crystal inside a four-mirror ring cavity singly resonant at the signal wavelength (1.4-1.7 μm). The 50 mm-long fanout crystal is pumped by a single-mode, narrow-line width continuous-wave 1064 nm fiber laser, which achieves an oscillation threshold of 2 W. For long-term frequency stabilization and control, we actively lock the OPO to an optical transfer cavity (OTC), which is in turn locked to a polarization-stabilized HeNe laser to achieve root-mean-square noise of ≤2.3(2) MHz within 10 ms and absolute OPO idler frequency drifts of <1 MHz/hour. The high output power and narrow line width of the OPO are demonstrated via saturated absorption spectroscopy on the ν3 P(7) transition of CH4 (40-300 mTorr) in a retroreflecting double-pass cell, for which narrow Lamb dips with a full width at half-maximum (fwhm) of 3.1(1) MHz are readily observed. Technical aspects of our monolithic laser block construction, thermal cooling, optical transfer cavity, electronic servo loop control, mirror selection, and beam size considerations for optimal low pumping threshold, long-term frequency stability, and maximal conversion efficiency are presented, with further details available on request.

Laser spectroscopy in the longwave mid-infrared (LWIR) region reveals the structures and properties of various biochemical substances. Here, we demonstrate a broadband LWIR laser covering 5.7–11.0 μm with 13 mW average power and 108 MHz repetition rate based on difference frequency generation (DFG) in a zinc germanium phosphide (ZGP) crystal. The laser can also be widely tuned over 4.6–11.0 μm with a maximum average power of 40 mW. The pump and signal pulses of DFG are generated from a broadband optical parametric oscillator (OPO) system pumped by a Yb-doped fiber laser. Absorption spectroscopy of an organic compound was demonstrated by the LWIR source. Furthermore, combining additional complex phase locking, it has the potential to achieve dual comb spectroscopy (DCS) for higher measurement speed and resolution. The adjustment-free LWIR lasers with instantaneous broadband spectra reduce system complexity and alignment difficulty, and they are desirable for sensitive parallel molecular spectroscopy and biological macromolecule detection.

Renormalization Method for Variable Stiffness in Fractal 2DOF Nonlinear Parametric Oscillators

We introduce the concept of a gain-switched diode-based fiber-feedback optical parametric oscillator with an intracavity echelle grating stretcher for time-dispersion wavelength tuning. Our approach enables four different tuning ranges corresponding to different grating orders in the stretcher. Within each tuning range, the wavelength is adjusted electronically by varying the pump laser's repetition rate. This approach maintains entirely static optics while delivering a narrow linewidth of less than 1 nm and a wavelength reproducibility of 2 pm. Time-dispersion wavelength tuning by a static echelle grating stretcher with grating-order multiplexing combines high repeatability, stability, and electronic tuning, and expands the tuning range by the number of grating orders. This concept can be transferred to other grating types and spectral ranges and is ideal for applications in infrared narrowband AM/WM spectroscopy.

Abstract Optical parametric oscillators (OPOs) have emerged as highly versatile platforms for signal processing, machine learning, and all-optical computation. In particular, integrated photonic circuits have demonstrated an efficient and scalable route to build OPO networks through time-multiplexing. However, for tasks requiring massive parallelism with low latency, spatial multiplexing with vertical micro-cavities is a more natural approach to overcome the shoreline density limits of edge-emitting photonics. To this end, we propose an approach to realizing vertical micro-cavity OPOs (VCOPOs) leveraging recent developments in micro-optical fabrication techniques. We consider thin film LiNbO3-filled dielectric micro-cavities as a case study, but the approach taken here is readily extended to any χ ( 2 ) nonlinear medium. Based on conservative industrial fabrication tolerances, we predict a minimal foot-print of ca. 5 × 5 μ m 2 , while achieving oscillation thresholds in the microwatts range. Advanced fabrication methods open a path toward sub-µW oscillation threshold, with a ratio of single-photon non-linear coupling rate to dissipation rate g / κ &gt; 5 % . We propose a theoretical framework for the classical and quantum operation of two dimensional arrays of VCOPOs, and discuss potential applications such as surface emitting devices, spatially multi-mode parametric amplifiers and squeezers, as well as optical simulators of classical and quantum Hamiltonians.

70.7% slope-efficiency, mid-infrared tunable Fe:ZnSe laser gain-switched by high-energy 3.47 μm KTA optical parametric oscillator and amplifier

We report, to the best of our knowledge, the first demonstration of dual-comb operation from a femtosecond optical parametric oscillator (OPO) at a 1-GHz pulse repetition rate. The singly-resonant OPO is fundamentally synchronously pumped by a high-power low-noise Yb:CaF2 diode-pumped solid-state laser, enabling a compact system design, high parametric gain, and stable uniform pulse trains for both the signal and idler outputs. Dual-comb generation is realized in a spatially multiplexed single-cavity configuration for both the OPO and the pump laser. The center wavelength is tunable from 1415 nm to 1645 nm (signal) and 2960 nm to 4085 nm (idler) with average powers up to 650 mW and 200 mW per comb, respectively. The source delivers on average an instantaneous bandwidth of 2.5 THz, a power-per-combline up to 270 µW in the short-wave infrared and 75 µW in the mid-wave infrared is available. We demonstrate the potential of this source for fast dual-comb spectroscopy by detecting ambient methane (∼2 ppm) at 1645.5 nm over a 41-m path length, achieving a normalized spectral signal-to-noise ratio of 42.0 dB Hz1/2. This measurement was performed without any active stabilization.

Temporal evolution of Wigner functions representing fluctuation distribution of magnetization in Y_{3}Fe_{5}O_{12} (YIG) at the moment of parametric oscillation onset has been investigated. Our newly developed time-resolved spectroscopy unmasks that highly distorted and stretched correlation of magnetization fluctuation leads the parametric oscillation, being consistent with numerical simulation incorporating nonlinear four-magnon scattering. The method offers a powerful tool for probing nonlinear dynamics in a variety of magnets.

Towards Room-Temperature Exciton–Polariton Supersolidity Driven by Guided Optical Parametric Oscillation

Improved conversion efficiency of mid-infrared MgO:PPLN optical parametric oscillator by optimizing pump pulse waveform

High repetition rate, tunable mid-infrared vortex beam generation based on ZGP optical parametric oscillator

Coupled Kerr parametric oscillators (KPOs) are a promising resource for classical and quantum analog computation, for example to find the ground state of Ising Hamiltonians. Yet, the state space of strongly coupled KPO networks is very involved. As such, their phase diagram sometimes features either too few or too many states, including some that cannot be mapped to Ising spin configurations. This complexity makes it challenging to find and meet the conditions under which an analog optimization algorithm can be successful. Here, we demonstrate how to use three strongly coupled KPOs as a simulator for an Ising Hamiltonian, and estimate its ground state using a Boltzmann sampling measurement. While fully classical, our Letter is directly relevant for quantum systems operating on coherent states.

Terahertz parametric generation (TPG) is one of the most promising techniques for developing high-performance terahertz sources, particularly through the use of sub-nanosecond laser pumping that simultaneously suppresses stimulated Brillouin scattering and enhances nonlinear gain. However, a fundamental challenge persists in achieving both high output power and broad tunability due to the lack of efficient seeding solutions. This study demonstrates a novel, to our knowledge, approach to address this issue, employing a high-power sub-nanosecond pump laser and a synchronized tunable nanosecond optical parametric oscillator (OPO) seeding system. The terahertz-wave tuning range of 0.55–13.6 THz was enabled by integrating two nonlinear crystals (MgO:CLN and KTP) and dual pump wavelengths (1064 and 532 nm). Operating at the repetition rate of 1 kHz, the maximum output power reached 1.06 mW at 1.68 THz with the peak power exceeding 1 kW, corresponding to the conversion efficiency of 1.25×10−4 and photon conversion efficiency of 2.1%. The TPG system offers high-power stability and good Gaussian beam profile, which is believed to be a significant leap of high-performance terahertz sources and holds great importance in applications like radar, imaging, and spectroscopy. An in-depth analysis was also given on the output characteristics according to the dynamics of the nonlinear processes, paving the way for power scaling.

Observing non-classical properties of light is a long-standing interest to advance a wide range of quantum applications. Optical cavities are essential to generate and manipulate non-classical light. However, detecting changes in cavity properties induced by the quantum state remains a critical challenge in the optical domain due to the weak material nonlinearity. Here, we propose a framework for observing the dynamics of quantum states generated inside nonlinear optical cavities. We leverage the symmetry-breaking process of a bistable system, which is highly sensitive to the initial state, enabling detection of quantum state displacement through an asymmetric equilibrium of a macroscopic observable. With a nonlinear response at the single photon level, our approach directly imprints the cavity field distribution onto the statistics of bistable cavity steady-states. We experimentally demonstrate our approach in a degenerate optical parametric oscillator, generating and reconstructing different quantum states. As a validation, we reconstruct the Husimi Q function of the cavity squeezed vacuum state. In addition, we observe the evolution of the quantum vacuum state inside the cavity as it undergoes phase-sensitive amplification. By enabling generation and measurement of quantum states in a single nonlinear optical cavity, our method paves a way for studying exotic dynamics of quantum optical states in nonlinear driven-dissipative systems.

A tunable and narrow-linewidth terahertz (THz) difference frequency generation (DFG) with DAST crystal was demonstrated based on near infrared pump in this paper. A dual-seeded KTP optical parametric oscillator (OPO) was constructed as a pump source for DFG. The THz frequency can be continuously tuned in the range of 1.1-8.0 THz. The maximum signal-to-noise ratio (SNR) of 40.5 dB was obtained at 4.315 THz. The linewidth of the output THz-wave was estimated to be less than 473 MHz by fitting transmission spectrum of CO gas at 1800Pa pressure around 49.93 cm-1 with the Voigt gas model. Furthermore, the THz spectral measurements of the mixture of CO gas and water vapor in air were in good agreement with their absorption lines in Hitran database. Additionally, the measurement of the transmission spectroscopy and the absorption coefficient of white PE tablet were demonstrated in wideband THz range. Such wide tunable THz source with narrow linewidth has good potential in THz high-precision spectroscopic detection.

This study investigates the interplay between high-frequency external forcing and the intrinsic dynamics of a quantum nonlinear parametric oscillator. To analyze this system, classical equationsof motion of the averages of quantum operators are derived and solved by employing suitable truncation schemes and the Blekhman perturbation method. It is observed that quantum fluctuations and oscillation amplitudes within the parametric resonance zone can be modulated through the fast external periodic forcing. Moreover, the influence of the strength of driving on the overall system dynamics is systematically explored. Finally, the theoretical predictions are validated through numerical simulations, establishing the reliability of the developed framework.

Abstract Tunable mid-infrared(MIR) and far-infrared(FIR) laser output was demonstrated based on BaGa4Se7 (BGSe) crystals and optical parametric oscillator (OPO). With a 1.06μm Nd:YAG laser and a double-pass singly-resonant OPO (DSRO) cavity, a laser energy output of 2.2 mJ at 10 μm was obtained. By tuning the angle and temperature, a tunable laser output covering the wavelength range from 6 to 17 μm was obtained with a tuning precision better than 3 nm. The corresponding optical-to-optical conversion efficiency was 2.8%, and the slope efficiency was 4.4%. The damage effect of the output laser on detectors was also investigated, and point damage to the detector occurred at an output energy of 16.4 μJ. The laser system has the advantages of miniaturization, wide tuning range, high energy, and high tuning resolution. Its broadband laser characteristics make it highly valuable for applications in atmospheric detection, infrared spectroscopy, and electro-optical countermeasures.