Optical Parametric Amplification System Research Articles

Mid-infrared optical parametric chirped-pulse amplifier at 50 W and 38 fs pumped by a high-power Yb-InnoSlab platform

High-power Yb:InnoSlab lasers are proliferating into multiple modern application areas of laser physics ranging from plasma physics and nanolithography to driving optical parametric amplifiers for high-harmonic generation and attosecond science. Here, we present, the layout, design and first results of an optical parametric chirped-pulse amplifier system pumped by a kW-level average power Yb-InnoSlab laser. We describe the layout and concepts of the pump lasers, with particular attention to the specific design principles required for our application. In the current configuration, the pump laser delivers up to 933 W, 18.7 mJ, 1.2 ps pulses at 50 kHz repetition rate. In a first attempt this has generated above 70 W average power at 2 μm via parametric amplification. Chirped-mirror compression resulted in mJ-level pulses at 50 W and 38-fs pulse duration (5.7 cycles at 2 μm).

Efficient single-cycle mid-infrared femtosecond laser pulse generation by spectrally temporally cascaded optical parametric amplification with pump energy recycling.

We proposed spectrally temporally cascaded optical parametric amplification (STOPA) using pump energy recycling to simultaneously increase spectral bandwidth and conversion efficiency in optical parametric amplification (OPA). Using BiB3O6 and KTiOAsO4 nonlinear crystals, near-single-cycle mid-infrared (MIR) pulses with maximum energy conversion efficiencies exceeding 25% were obtained in simulations. We successfully demonstrated sub-two-cycle, CEP-stable pulse generation at 1.8 µm using a four-step STOPA system in the experiment. This method provides a solution to solve the limitations of the gain bandwidth of nonlinear crystals and the low conversion efficiency in broadband OPA systems, which is helpful for intense attosecond pulse generation and strong laser field physics studies.

A versatile and narrow linewidth infrared radiation source for ro-vibration state-selected preparation of molecules in molecular beams.

We describe the design and characterization of a versatile pulsed (5ns, 10Hz repetition rate) optical parametric oscillator and amplifier system capable of generating single longitudinal mode, narrow linewidth (0.01 cm-1) radiations in the wavelength range of 680-870nm and 1380-4650nm. Using a combination of power-normalized photoacoustic signal and a Fizeau interferometer-based wavemeter, we are able to actively stabilize the output wavenumber to within 0.005 cm-1 (3σ) over a timescale longer than 1000s. We demonstrate an application of this system by performing ro-vibration state-selected preparation of CO in the v = 2 state, via direct overtone excitation (v = 0 → 2 at 2346nm) and subsequent state-selected detection in an internally cold molecular beam.

Rapid photo-bleaching gamma irradiated Yb-doped optical fibers by high-energy ns pulsed laser

A rapid and efficient photo-bleaching process was demonstrated with a high-energy nanosecond pulse to recover existing and/or revealed color centers on 10 kGy Gamma-irradiated Yb-doped optical fiber. Multi-mJ pulsed laser based on an optical parametric amplifier system operating at wavelengths of 532 nm, 680 nm and 793 nm was used. The photo-bleaching performance is investigated as a function of the wavelength and energy of the pulsed light source. It was observed that the photo-bleaching level of the Yb-doped optical fiber increased when the exposure time of the pulsed laser light and the photon energy was increased. The maximum PB occurred in the pulsed laser of 532 nm wavelength in the optical fiber. Also, a drastically increase in the PB was observed due to the increasing laser energy at the wavelength of 532 nm and 680 nm pulsed laser. The results show that the recovery levels of color centers in the Yb-doped optical fibers could be reached up to 96 % in a shorter time (h) by using the pulsed laser compared to that of the studies using continuous laser.

Investigation of the Amplified Spontaneous Emission Threshold of Cesium Lead Bromide Perovskite Quantum Dots at Different Excitation Wavelengths

The goal of this research is to see how excitation wavelength affects steady-state photoluminescence (PL), time-resolved photoluminescence (TRPL), and amplified spontaneous emission (ASE) in CsPbBr3 perovskite quantum dots (PQD). At PL and ASE, a plausible mechanism for explaining the excitation wavelength-dependent phenomena was proposed. The PL and ASE properties of CsPbBr3 PQD as optical materials were examined experimentally at excitation wavelengths of 355–450 nm. An optical parametric amplifier system was used to accomplish optical pumping utilizing a laser pulse with a pulse duration of 70 ps. The ASE threshold was explored and compared the ratio of photons in the pump pulse to band gap energies. The excitation wavelength (λ ex) has a considerable influence on the ASE behavior, with high optical densities correlating to optimal excitation, as evidenced by the absorption spectrum, which has a larger absorption coefficient. Furthermore, the energy density at the ASE threshold was closely correlated with the λ ex following the absorption spectrum. Also, it has been demonstrated that changing the excitation wavelength reduces the PQD PL lifetime. Finally, electron-hole pairs can be produced at a reasonable depth from the film’s surface using the appropriate excitation wavelength.

Generation of large-scale continuous-variable cluster states multiplexed both in time and frequency domains.

A large-scale continuous variable (CV) cluster state is necessary in quantum information processing based on measurement-based quantum computing (MBQC). Specially, generating a large-scale CV cluster state multiplexed in a time domain is easier to implement and has strong scalability in experiment. Here one-dimensional (1D) large-scale dual-rail CV cluster states multiplexed both in time and frequency domains are parallelly generated, which can be further extended to a three-dimensional (3D) CV cluster state by combining two time-delay nondegenerate optical parametric amplification systems with beam-splitters. It is shown that the number of parallel arrays depends on the corresponding frequency comb lines, the partite number of each array can be very large (million), and the scale of the 3D cluster state can be ultra-large. In addition, the concrete quantum computing schemes of applying the generated 1D and 3D cluster states are also demonstrated. Our schemes may pave the way for fault-tolerant and topologically protected MBQC in hybrid domains, by further combining with efficient coding and quantum error correction.

Versatile few-cycle high-energy MID-IR OPCPA for nonlinear optics, spectroscopy and imaging

High-power, high-energy, ultrashort, mid-infrared (MID-IR) laser systems operating at high repetition rates are of considerable interest for many science applications, such as coherent vibrational spectroscopy, label-free imaging, time-resolved pump-probe and high-harmonic generation studies. We developed an optical parametric chirped-pulse amplifier (OPCPA) system employing a difference-frequency generation in a lithium gallium sulfide nonlinear crystal in the final amplifier stage, which provides in principle the possibility for passive carrier-envelop-phase (CEP) stability. The OPCPA efficiently down-converts a 1 μm 200 μJ Yb-YAG pump pulse into the MID-IR spectral range generating μJ-level pulses at a repetition rate of 200 kHz. Two modes of operations providing complimentary MID-IR pulse properties are presented. Depending on the envisaged application, one can switch between (a) a wavelength-tunable (4.2–11 μm) source and (b) a broadband source centered at ≈8.5 μm by controlling the group-delay dispersion of the signal pulse. The broadband, high-energy MID-IR pulses have a short pulse duration of 74±2 fs, which corresponds to only ≈3 optical cycles at the central wavelength of 8.5 μm.

High-Speed Mid-Wave Infrared Uni-Traveling Carrier Photodetector Based on InAs/InAsSb Type-II Superlattice

High-speed photodetectors operating at mid-wave infrared are crucial for free-space optical communication and frequency comb spectroscopy. In this letter, we report a high-speed mid-wave infrared uni-traveling carrier photodiode based on InAs/InAsSb type-II superlattice at room temperature for the first time. The device exhibits a cut-off wavelength of around 5.5 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> at room temperature. The responsivity of the device is about 0.6 A/W (at 4.5 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>) under &#x2212;1 V at room temperature. The frequency response of the device is characterized by an optical parametric amplification system generating mid-infrared femtosecond pulses. A device with a 20 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> diameter has a 3-dB bandwidth of 12.8 GHz at &#x2212;4 V. These promising results suggest that the device could be potential candidates to be employed in the emerging high-speed MWIR applications.

Investigation of a widely-tunable subnanosecond BBO-based optical parametric amplifier

We report an experimental realization of a subnanosecond optical parametric amplifier (OPA) system in a beta barium borate (BBO) crystal pumped by the third harmonic of a passively Q-switched Nd:YAG microlaser system and seeded by the continuum generated in a photonic crystal fibre (PCF). It yields broadband continuous signal wavelength tunability in the visible spectrum range from 470 to 660 nm and the idler wavelength from 768 to 1450 nm. Besides the experimental data, the numerical simulation results of the BBO optical parametric amplifier are presented. The maximum output power of the subnanosecond BBO OPA is limited by laser induced damage in the BBO crystal by the pump radiation and seed radiation spectral power density. We also notice and discuss the effect of seed radiation on BBO OPA output radiation characteristics. The numerical simulations qualitatively agree with the experimental data.

Modeling pulse propagation in fiber optical parametric amplifier by a long short-term memory network

The ultrashort pulse evolution in fiber optical parametric amplifier (FOPA) systems is a highly complex nonlinear dynamic. Here, the long short-term memory network (LSTM) is applied to predicting the pulse propagation of signal waves in the FOPA system, rather than calculating the nonlinear Schrödinger equation (NLSE) numerically. The LSTM network only requires the initial signal power waveform, and the signal pulse propagation is realized in the feedback loop. Besides, we focus on predicting the evolution of signal pulse by varying the initial signal power and the initial signal pulse width to test the performance of our proposed method. The predictions of the LSTM network show great consistency with the NLSE results in each propagation stage of two cases, which reveal that the signal pulse evolution in FOPA is achieved precisely. The realization reduces the computational burden and further gives an effective way to optimize and guide the experiment and application in the FOPA systems.

Subnanosecond widely-tunable in the visible spectrum range LBO based optical parametric amplifier

We report realization of a widely-tunable subnanosecond optical parametric amplifier system in LBO crystal pumped by third harmonic of a passively Q-switched Nd:YAG microlaser system. It yields continuous signal wavelength tunability in the visible spectrum range from 460 to 680 nm and idler wavelength — from 740 to 1500 nm. We present experimental data and numerical simulations of our optical parametric amplifier and discuss future improvement directions for greater pump to signal conversion efficiency.

Deep learning based pulse prediction of nonlinear dynamics in fiber optics

The initial state of a nonlinear optical fiber system plays a vital role in the ultrafast pulse evolution dynamic. In this work, a data-driven compressed convolutional neural network, named inverse network, is proposed to predict initial pulse distribution through a series of discrete power profiles at different propagation distances. The inverse network is trained and tested based on two typical nonlinear dynamics: (1) the pulse evolution in a fiber optical parametric amplifier system and (2) soliton pair evolution in high-nonlinear fibers. Great prediction accuracy is reached when the epoch grows to 5000 in both cases, with the normalized root mean square errors below 0.01 on the entire testing set. Meanwhile, the lightweight network is highly effective. In this work, it takes approximately 30 seconds for 5,000 epochs training with a dataset size of 900. The inverse network is further tested and analyzed on the dataset with different signal-to-noise ratios and input sizes. The results show fair stability at the deviation on the testing set. The proposed inverse network demonstrates a promising approach to optimizing the initial pulse of fiber optics systems.

High-energy nanosecond parametric source at 2.7 µm.

We report a high-energy nanosecond KTiOAsO4-based optical parametric oscillator and amplifier system driven by a 1064-nm, injection-seeded, Q-switched Nd:YAG laser to provide mid-infrared pumping for few-cycle optical parametric chirped-pulse amplification operating in the long-wave infrared spectral regime. An output energy of 10.5 mJ at 2726 nm was obtained from the final power amplifier with a spectral width of 2.8 nm, pulse duration of 1.2 ns, and M2 value of 2.4. The parametric source provides for the second mode of operation, where 10-ns pulses are produced by disabling the electro-optic slicing that enables the 1-ns mode. For 10-ns operation, the source produced energy of 25 mJ with a M2 value of 2.8.

Phase Compensation Method in OPA System Based on the Linear Electro-Optic Effect

Factors such as mechanical deformation and temperature changes lead to phase mismatch in optical parametric amplification systems, impacting energy stability. A phase compensation method via the linear electro-optic effect can overcome this limitation. Phase mismatch compensation characteristics were simulated via the linear electro-optic effect in 70%-deuterated DKDP and 95%-deuterated DKDP. This method was applied to OPA systems to verify its feasibility. The results show that the temperature acceptance bandwidth of 70%-deuterated DKDP and 95%-deuterated DKDP can be ~1.75 and ~2 times larger, respectively, than that of the OPA without compensation. Moreover, the angle acceptance bandwidth of 70%-deuterated DKDP and 95%-deuterated DKDP can be ~2 times larger than that of the OPA without compensation. The abovementioned method can facilitate the compensation of phase mismatch within a range and can be widely used in OPA and optical parametric chirped pulse amplification systems to improve laser stability.

Widely-tunable synchronisation-free picosecond laser source for multimodal CARS, SHG, and two-photon microscopy

We demonstrate a continuous wave (CW) seeded synchronization-free optical parametric amplifier (OPA) pumped by a picosecond, 1 µm laser and show its performance when used as a simple yet powerful source for label-free coherent anti-Stokes Raman scattering (CARS), concurrent second harmonic generation (SHG), and two-photon fluorescence microscopy in an epi-detection geometry. The average power level of above 175 mW, spectral resolution of 8 cm−1, and 2 ps pulse duration are well optimized for CARS microscopy in bio-science and bio-medical imaging systems. Our OPA is a much simpler setup than either the “gold-standard” laser and optical parametric oscillator (OPO) combination traditionally used for CARS imaging, or the more recently developed OPA systems pumped with femtosecond pulses [1]. Rapid and accurate tuning between resonances was achieved by changing the poled channels and temperature of the periodically-poled lithium niobate (PPLN) OPA crystal together with the OPA seed wavelength. The Pump-Stokes frequency detuning range fully covered the C-H stretching band used for the imaging of lipids. By enabling three multiphoton techniques using a compact, synchronization free laser source, our work paves the way for the translation of label-free multi-photon microscopy imaging from biomedical research to an imaging based diagnostic tool for use in the healthcare arena.

High-power few-cycle near-infrared OPCPA for soft X-ray generation at 100 kHz.

We present a near-infrared optical parametric chirped-pulse amplifier (OPCPA) and soft X-ray (SXR) high-harmonic generation system. The OPCPA produces few-cycle pulses at a center wavelength of 800 nm and operates at a high repetition rate of 100 kHz. It is seeded by fully programmable amplitude and phase controlled ultra-broadband pulses from a Ti:sapphire oscillator. The output from the OPCPA system was compressed to near-transform-limited 9.3-fs pulses. Fully characterized pulse compression was recorded for an average power of 22.5 W, demonstrating pulses with a peak power greater than 21 GW. Without full temporal characterization, high-power operation was achieved up to 35 W. We demonstrate that at such high repetition rates, spatiotemporally flattened pump pulses can be achieved through a cascaded second-harmonic generation approach with an efficiency of more than 70%. This combination provides a compelling OPCPA architecture for scaling the peak power of high-repetition-rate ultra-broadband systems in the near-infrared. The output of this 800-nm OPCPA system was used to generate SXR radiation reaching 190 eV photon energy through high-harmonic generation in helium.

11.6 W middle infrared ZnGeP2 optical parametric amplifier system with a 1 kHz repetition rate

We demonstrated a 11.6 W middle infrared ZnGeP2 (ZGP) optical parametric amplifier (OPA), which was pumped by a 2090.7 nm Q-switched Ho:YAG laser with a pulse repetition frequency of 1 kHz. The output power of 2.2 W produced by a ZGP optical parametric oscillator (OPO) served as seed and the whole pump power of ZGP OPA with ZGP OPO was 24 W, corresponding to an optical-to-optical conversion efficiency of 48.3% from the Ho to the middle infrared. At the maximum output level, the beam quality factors M2 of the middle infrared ZGP OPA were 2.2 and 2.4 for horizontal and vertical directions, respectively. The linewidths (FWHM) of the middle infrared ZGP OPA spectrum were about 172 nm and 121 nm for the signal and idler with a central wavelength of 3.85 μm and 4.58 μm, respectively.

High-beam-quality 2.1 µm pumped mid-infrared type-II phase-matching BaGa4Se7 optical parametric oscillator with a ZnGeP2 amplifier.

We firstly demonstrated a tunable 2.1 µm pumped mid-infrared type-II phase-matching BaGa4Se7 (BGSe) optical parametric oscillator (OPO). A signal tuning range of 3.82-3.99 µm was achieved. With a signal light produced by the BGSe OPO serving as seed, the ZnGeP2 (ZGP) optical parametric amplifier (OPA) was first introduced. A 4.35 W mid-infrared laser was obtained in the novel type-II BGSe OPO with a ZGP OPA system, which was pumped by a 24 W 1 kHz Q-switched Ho:YAG laser. The beam quality factor M2 of the whole system is ∼2.3, which is over a 50% promotion on the previous M2 results of single BGSe OPO.

Nonlinear optical absorption properties of tellurium glasses containing different network modifiers

Linear- and nonlinear-optical absorption and carrier dynamic properties of binary tellurite glasses modified with different amount of WO3, Nb2O5, and ZnO were investigated via UV–Vis spectrophotometer, open aperture Z-scan and pump-probe techniques. Glasses were synthesized using conventional melt quenching technique. The vitreous nature of the samples were confirmed by conducting XRD measurements. The studied glasses have got absorption spectra similar to that of the semiconductor materials and it is found that the absorption edges of the samples blue-shifted with the changing amount and the type of the network modifier. Nonlinear absorption measurements of samples were carried out using a laser source with 532 nm wavelength, 10 Hz repetition rate and 4 ns pulse duration. All of the samples showed nonlinear absorption behavior. The transmission pump-probe spectroscopy experiments were carried out to investigate the ultrafast carrier dynamics of studied glasses with the help of Ti:sapphire laser amplifier optical parametric amplifier system with 100 fs pulse duration. The experiments were established by excitation of glasses with 400 nm pump and 500 nm probe lights. The results of the measurements indicated that the two-photon absorption and two-photon assisted free carrier absorption mechanisms are responsible for the nonlinear optical processes. In the light of obtained linear and nonlinear optical results, it can be easily concluded that these glasses are very useful for LED, optical amplifier, data storage, and laser host applications

Preliminary results on non-linear effects in Au-ion-doped glass materials irradiated by femtosecond laser pulses

Our research was motivated by the specific properties of noble-metal nanoparticles and their wide applications. The resonance frequency for noble-metal nanostructures is in the near-UV and visible spectral ranges, where most of the commercially-available lasers oscillate. This makes these materials attractive candidates for studying their properties in view of efficient applications. We investigated filaments formation in Au-ion-doped glass materials, transparent in the visible range, during irradiation by femtosecond laser pulses. Second harmonic generation in the media was observed as well. This proved the formation of polycrystalline structures inside the media after femtosecond laser radiation. Further, self-phase modulation and continuum were observed. Thus, the nonlinearity of the media is higher than that of glass not doped with noble-metal particles. The nonlinear effects in the samples were investigated in terms of the laser beam parameters. The laser energy applied was between 10 – 40 μJ. The wavelengths used were in the range 240 – 2600 nm, as generated by an optical parametric amplifier system (TOPAS). The regenerative Ti:Sapphire amplified laser system emits at a central wavelength of 800 nm with a pulse duration of 35 fs and 1-kHz repetition rate.