Optical Parametric Amplifier Research Articles

Efficient noncollinear optical parametric chirped-pulse amplification in oversaturation region

Optical parametric chirped pulse amplification (OPCPA) is the workhorse to generate intense ultrashort pulses across a broad wavelength range. Typically, OPCPA operates in the saturation region, but barely in the oversaturation region due to efficiency drop caused by back conversion. Through numerical simulations, we reveal the potential of noncollinear OPCPA to achieve significantly higher conversion efficiency in the oversaturation regime compared to the recognized saturation efficiency. This enhancement stems from the suppression of back conversion facilitated by noncollinearity-induced idler dissipation. Besides offering high efficiency and robustness, the oversaturated noncollinear OPCPA also exhibits acceptable spatial and temporal properties, as well as spatiotemporal coupling properties. These findings hold promise for enhancing the final stage of a noncollinear OPCPA system, where a high conversion efficiency is essential.

Plasmonic tuning of nano-antennas for super-gain light amplification

Nanoscale conductive materials are often used for inducing localized free electron oscillations known as plasmons. This is due to their high electronic excitability under optical irradiation owing to their super-small volume. Recently, plasmons have been of interest for enhancing the gain-bandwidth product of optical amplifiers. There are currently two well-established mechanisms for light amplification. The first one is via stimulated emission of radiation (lasers) using a given energy source and often an optical feedback mechanism. The second one is based on the nonlinear coupling of a low-intensity input wave and a high-intensity pump wave for energy exchange (parametric amplifiers). Both techniques have shortcomings. Lasers have a small operation bandwidth and offer a limited gain, but require moderate energy pumping to operate. Whereas optical parametric amplifiers (OPAs) offer a high operation bandwidth along with a much higher optical gain, with the drawback of requiring intense pumping to be functional. The aim of this paper is to introduce a technique that combines the advantages and eliminates the drawbacks of both techniques in the nanoscale to allow for a better amplification performance in integrated optical devices. This is achieved by inducing a plasmonic chirp in conductive nanomaterials a.k.a nano-antennas, which enables the confinement of an enormous electric energy density that can be coupled to an input beam for amplification. Using the Finite Difference Time Domain numerical-method with the material parameters of well-known semiconductors, intramaterial condensation of electric energy density is observed in semiconductor nano-antennas for certain plasmonic chirp-frequencies which enables broadband high-gain optical amplification based on free-electron oscillations that is promising for small-scale optical devices requiring a high gain-bandwidth product. The results are in good agreement with semiempirical data.

Quadripartite quantum steering generated by single-pass cascaded nonlinear processes

Quantum steering has become an important resource for quantum information due to its unique asymmetry. In this paper, quadripartite quantum steering generated by single-pass nondegenerate optical parametric amplification cascaded with a sum-frequency process is investigated. Firstly, an idler beam is produced by a different-frequency process between pump and signal. Secondly, a sum-frequency beam is generated by a cascaded sum-frequency process between idler beam and pump in the same optical superlattice. Quadripartite quantum steering among pump, signal, idler and sum-frequency beams is demonstrated based on the criterion for multipartite quantum steering. The influences of nonlinear coupling coefficients κ, dimensionless propagation length ξ, and the initial values of pump and signal on the variation characteristic of the quadripartite steering are also investigated. The results indicate that slightly larger nonlinear coupling coefficients of cascaded nonlinear processes and weaker signals can achieve better quadripartite quantum steering. This simple quadripartite quantum steering preparation scheme does not require a resonant cavity and is easier to implement experimentally, with potential applications in quantum communication and computing.

H2 chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering thermometry at high temperature and pressure

This article describes the development and application of hydrogen (H2) chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) in high-temperature and high-pressure conditions. H2 fs CARS thermometry was performed in Hencken burner flames up to 2300 K, as well as in a heated gas-cell at temperatures up to 1000 K. It was observed that the H2 fs CARS spectra are highly sensitive to the pump and Stokes chirp. Chirp typically originates from optical components or systems such as windows, polarizers, and the optical parametric amplifier. As a result, the pump delay is modeled to provide a shift to the Raman excitation efficiency curve. With the updated theoretical model, excellent agreement was found between the simulated and experimental spectra. The mean error and precision are 2.8% and 2.3%, respectively. In addition, the spectral phase of the input pulses and the pump time delay determined from the experimental spectra closely align with the theoretical predictions. It is also found that pressure does not have significant effects on the H2 fs CARS spectra up to 5 MPa at 1000 K. The collision model provides excellent agreement with the experiment. This allows the use of low-pressure laser parameters for high-pressure thermometry measurements.

Coherent feedback enhanced quantum-dense metrology in a lossy environment.

Quantum dense metrology (QDM) performs high-precision measurements by a two-mode entangled state created by an optical parametric amplifier (PA), where one mode is a meter beam and the other is a reference beam. In practical applications, the photon losses of meter beam are unavoidable, resulting in a degradation of the sensitivity. Here, we employ coherent feedback that feeds the reference beam back into the PA by a beam splitter to enhance the sensitivity in a lossy environment. The results show that the sensitivity is enhanced significantly by adjusting the splitting ratio of the beam splitter. This method may find its potential applications in QDM. Furthermore, such a strategy that two non-commuting observables are simultaneous measurements could provide a new way to individually control the noise-induced random drift in phase or amplitude of the light field, which would be significant for stabilizing the system and long-term precision measurement.

Crystal growth, structure, spectral and thermal properties of ScxY1-xCOB single crystals

Yttrium calcium oxyborate (YCOB) crystals are excellent nonlinear optical crystals. To enhance the thermal properties of YCOB crystal, Sc-doped YCOB crystals, denoted as ScxY1-xCa4O(BO3)3 (x = 0.1 and 0.2) were grown using the Czochralski method along the b-direction. Various measurements, including X-ray powder diffraction, rocking curve analysis, inductively coupled plasma-optical emission spectroscopy (ICP-OES), transmission spectroscopy, density measurements, and thermal property assessments, were conducted to evaluate the characteristics of the ScxY1-xCOB crystals. The results indicated that ScxY1-xCOB crystals have an isostructural arrangement like YCOB, with segregation coefficients of approximately 0.2. The full width at half maximum (FWHM) values of the rocking curves of the ScxY1-xCOB (x = 0.1 and 0.2) crystals are 33.9″ and 29.3″, respectively. Furthermore, the specific heat, thermal diffusion coefficients and thermal conductivity of the ScxY1-xCOB crystals were examined in the temperature range of 298–573 K, which were found to be higher than those of pure YCOB. These high-quality ScxY1-xCOB crystals are expected to serve as suitable nonlinear optical crystals media for optical parametric chirped pulse amplification (OPCPA) applications.

Degradation of temporal contrast from post-pedestal interference with a chirped pulse in an optical parametric amplifier.

Pre-pedestal generation is observed in a 0.35-PW laser front end coming from a post-pedestal via instantaneous gain and pump depletion in an optical parametric amplifier during chirped-pulse amplification. Generalized simulations show how this effect arises from gain nonlinearity and applies to all optical parametric chirped-pulse-amplification systems with a post-pedestal. An experiment minimizing the effect of B-integral is used to isolate and study the newly observed conversion of a continuous post-pedestal into a continuous pre-pedestal. Matching numerical simulations confirm experimental results and additionally reveal how third-order dispersion largely controls the slope of the generated pre-pedestal.

Toward high-energy few-cycle optical vortices with minimized topological charge dispersion.

A simple approach to generate high-energy few-cycle optical vortices with minimized topological charge dispersion is introduced. By means of numerical simulations, it is shown that, by leveraging the intrinsic properties of optical parametric chirped pulse amplification (OPCPA), clean transfer of topological charge from a high-energy narrowband pump pulse to a broadband idler is feasible under certain particular conditions, enabling the generation of high-energy few-cycle vortex pulses with extremely low topological charge dispersion.

Dispersion‐Engineered Super‐Gain Parametric Amplification in Nanoscale Optical Cavities

The gain factor of the optical parametric amplification (OPA) process is known to be negligible in the small scale due to low‐interaction‐medium length. Hence, in the nanoscale, OPA is deemed as infeasible. Therefore, in small‐scale‐integrated optical devices, stimulated‐emission‐based amplifiers (lasers) are employed instead of OPAs. In contrast, the major advantage of OPAs over lasers is that unlike lasers which only provide amplification over a narrow spectral band, OPAs provide high‐gain amplification over a very large, user‐controlled spectral band. In this article, it is shown that OPA can yield wideband high‐gain amplification over a nanoscale beam propagation distance through dispersion engineering. This is achieved by a proper tuning of the pump (source) wave frequency, which can maximize the effective medium nonlinearity by a few orders of magnitude, while concurrently maximizing the intracavity energy density, thereby compensating for the small co‐propagation distance for the input (signal) and pump beams. In this study, it is shown that an input wave can be amplified by a factor in a nanoscale cavity via precise dispersion engineering. Both empirical and computational formulations are used for the investigation, which display a reasonable agreement.

Comparative study of single pump all optical fiber amplifiers (POAs) with ultra wide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers

Abstract This paper has clarified comparative study of single pump all optical fiber amplifiers with ultrawide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers. Different amplifiers gain is demonstrated versus system distance for different light amplifiers in highly nonlinear fiber channel. As well as amplifier gain is clarified against system distance for different light amplifiers in DCF, DSF and NZDSF fiber channel. The mechanism of generation of single idler signal is studied based on single signal and pump signal. Moreover the mechanism of generation of single idler signal is analyzed and investigated clearly based on signal and two pump signals. Amplifier bandwidth is demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. The map of the signal losses is discussed and clarified versus wavelength band in the presence of all amplification techniques. Light signal per noise ratio and bit error rates are demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. POA is more suitable for the operation in HNLF fiber channel in compared to other proposed fiber communication channels. All optical amplifiers operation performance gain efficiency is compared together in different fiber channel media. The system can be employed with POAs for the fiber reach up to 100 km distance with a suitable amplifier gain and bandwidth. An important criteria for any amplifier is its gain and bandwidth for the compensation of the system loss and dispersion together. The optimum suitable pumping power is clarified for upgrade the system amplifier performance signature.

Generating superposition of squeezed states and photon-added squeezed states

The scheme of an arrangement is considered for the preparation of some non-classical superposed states from squeezed states by using the optical parametric amplifier (OPA) apparatus, which is based on an idea recently proposed to generate photon-added states from the coherent states of light. This technique allows one to obtain linear combinations of squeezed vacuum states (SVSs) and n-photon-added squeezed vacuum states (n-PASVSs), that can enrich the non-classicality of the SVSs and n-PASVSs and improve their performances in quantum information protocols. Their characteristics are greatly affected by the gain of the OPA and the coherent field amplitude (or, mean number of photons). For this purpose, a comprehensive analysis of the non-classical features of these states has been presented in four different behavioral regimes, i.e. low- and high-gain regimes in the presence of weak and strong coherent fields. Finally, the role of the gain parameter of the light state from OPA as one of the input states of the Mach–Zehnder interferometer (MZI) apparatus in phase sensitivity optimization is discussed.

Vortex plate retarder-based approach for the generation of sub-20 fs light pulses carrying orbital angular momentum

We use a vortex retarder-based approach to generate few optical cycles light pulses carrying orbital angular momentum (OAM) (known also as twisted light or optical vortex) from a Yb:KGW oscillator pumping a noncollinear optical parametric amplifier generating sub-10 fs linearly polarized light pulses in the near infrared spectral range (central wavelength 850 nm). We characterize such vortices both spatially and temporally by using astigmatic imaging technique and second harmonic generation-based frequency resolved optical gating, respectively. The generation of optical vortices is analyzed, and its structure reconstructed by estimating the spatio-spectral field and Fourier transforming it into the temporal domain. As a proof of concept, we show that we can also generate sub-20 fs light pulses carrying OAM and with arbitrary polarization on the first-order Poincaré sphere.

Optomechanically induced transparency in a hybrid system containing two-level atomic ensemble and optical parametric amplifier

We investigate the physical properties of multiple optomechanically induced transparency in a system. The system consists of two charged mechanical resonators and an optical cavity. An optical parametric amplifier (OPA) and a two-level atom ensemble are filled into the optical cavity. Some physical phenomena appear in the system driven by the probe field and the pump field. The width of transparent windows can be manipulated by the coupling strengths of the system. Specifically, the width of the transparency window increases with an increase in the parametric gain of the optical parametric amplifier (OPA). Furthermore, the number of transparent windows and the location of transparent points are also affected by the system parameters. The presence of two-level atomic ensemble causes the double transparent windows to be split three transparent windows. The Coulomb coupling between the two charged mechanical resonators causes the transparent points to move. Our approach provides a great flexibility for manipulating multiple induced transparency. It is helpful to study the quantum properties of nonlinear optical systems.

Direct sampling of femtosecond electric-field waveforms from an optical parametric oscillator

Detecting the electric-field waveform of an optical pulse from the terahertz to the visible spectral domain provides a complete characterization of the average field waveform and holds great potential for quantum optics, time-domain (including frequency-comb) spectroscopy, high-harmonic generation, and attosecond science, to name a few. The field-resolved measurements can be performed using electro-optic sampling, where a laser pulse is characterized through an interaction with another pulse of a much shorter duration. The measured pulse train must consist of identical pulses, including their equal carrier-envelope phase (CEP). Due to the limited coverage of broadband laser gain media, creating CEP-stable pulse trains in the mid-infrared typically requires nonlinear frequency conversion, such as difference frequency generation, optical parametric amplification, or optical rectification. These techniques operate in a single-pass geometry, often limiting efficiency. In this work, we demonstrate field-resolved analysis of the pulses generated in a resonant system, an optical parametric oscillator (OPO). Due to the inherent feedback, this device exhibits a relatively high conversion efficiency at a given level of input power. By electro-optic sampling, we prove that a subharmonic OPO pumped with CEP-stable few-cycle fiber-laser pulses generates a CEP-stable mid-infrared output. The full amplitude and phase information renders dispersion control straightforward. We also confirm the existence of an exotic “flipping” state of the OPO directly in the time domain, where the electric field of consecutive pulses has the opposite sign.

Ultrarelativistic electron beams accelerated by terawatt scalable kHz laser

We show the laser-driven acceleration of unprecedented, collimated (2 mrad divergence), and quasi-monoenergetic (25% energy spread) electron beams with energy up to 50 MeV at 1 kHz repetition rate. The laser driver is a multi-cycle (15 fs) 1 kHz optical parametric chirped pulse amplification system, operating at 26 mJ (1.7 TW). The scalability of the driver laser technology and the electron beams reported in this work pave the way toward developing high-brilliance x-ray sources for medical imaging and innovative devices for brain cancer treatment and represent a step toward the realization of a kHz GeV electron beamline.

Spatiotemporal dispersion compensation for a 200-THz noncollinear optical parametric amplifier.

A noncollinear optical parametric amplifier (NOPA) can produce few-cycle femtosecond laser pulses that are ideally suited for time-resolved optical spectroscopy measurements. However, the nonlinear-optical process giving rise to ultrabroadband pulses is susceptible to spatiotemporal dispersion problems. Here, we detail refinements, including chirped-pulse amplification (CPA) and pulse-front matching (PFM), that minimize spatiotemporal dispersion and thereby improve the properties of ultrabroadband pulses produced by a NOPA. The description includes a rationale behind the choices of optical and optomechanical components, as well as assessment protocols. We demonstrate these techniques using a 1kHz, second-harmonic Ti:sapphire pump configuration, which produces ∼5-fs duration pulses that span from about 500 to 800nm with a bandwidth of about 200THz. To demonstrate the utility of the CPA-PFM-NOPA, we measure vibrational quantum beats in the transient-absorption spectrum of methylene blue, a dye molecule that serves as a reference standard.

L- and U-Band WDM Transmission Over 6 THz Using PPLN-Based Optical Parametric Amplification and Wavelength-Band Conversion

L- and U-Band WDM Transmission Over 6 THz Using PPLN-Based Optical Parametric Amplification and Wavelength-Band Conversion

Femtosecond fluorescence conical optical parametric amplification spectroscopy.

Parametric superfluorescence (PSF), which originated from the optical amplification of vacuum quantum noise, is the primary noise source of femtosecond fluorescence non-collinear optical parametric amplification spectroscopy (FNOPAS). It severely affects the detection limit of FNOPAS to collect the femtosecond time-resolved spectra of extremely weak fluorescence. Here, we report the development of femtosecond fluorescence conical optical parametric amplification spectroscopy (FCOPAS), aimed at effectively suppressing the noise fluctuation from the PSF background. In contrast to traditional FNOPAS configurations utilizing lateral fluorescence collection and dot-like parametric amplification, FCOPAS employs an innovative conical fluorescence collection and ring-like amplification setup. This design enables effective cancellation of noise fluctuation across the entire PSF ring, resulting in an approximate order of magnitude reduction in PSF noise compared to prior FNOPAS outcomes. This advancement enables the resolution of transient fluorescence spectra of 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM) dye molecules in ethanol, even at an optically dilute concentration of 10-6 mol/l, with significantly enhanced signal-to-noise ratios. This improvement will be significant for extremely weak fluorescence detection on the femtosecond time scale.

Noncollinear Optical Parametric Amplification of Broadband Infrared Sum Frequency Generation Vibrational Spectroscopy.

Sum-frequency generation (SFG) vibrational spectroscopy is an invaluable tool in surface science, known for its specificity to surfaces and interfaces. Despite its wide application, it is often hampered by weak signal detection. Here, we present an innovative enhancement technique of postsample amplification, using a picosecond noncollinear optical parametric amplifier (NOPA). We conducted a systematical investigation into the impact of different intensities of pump and SFG seed light, as the input signal in NOPA, and demonstrated this method on the octadecanethiol (ODT) molecules on gold films. The amplified SFG by NOPA reproduced the SFG vibrational spectra, enhanced by about 4 orders of magnitude but with broader spectral resolution due to the short pulse width of the pump light in NOPA. This study makes it possible to realize highly sensitive SFG measurements, marking a significant advancement in spectroscopic analysis techniques.

Transmission of signal and idler using optical parametric amplifier based on PPLN waveguide

In this study, we attempted the repeated transmission of S-band signals by compensating for the loss of the transmission fiber using an optical parametric amplifier (OPA) based on a periodically poled LiNbO3 waveguide. We examined and compared the two configurations. The first method involved wavelength conversion of the signal to an idler, while the second method amplified the signal itself. In the latter case, we demonstrated repeated transmissions using external dispersion compensation. In the former case, we demonstrated that it was possible not only to compensate for fiber loss but also to reduce the accumulation of dispersion in transmission fibers by utilizing spectral inversion.