Fiber-laser-pumped, high-energy, mid-IR, picosecond optical parametric oscillator with a high-harmonic cavity
L. Xu, H.-Y. Chan, S. Alam, D. J. Richardson, and D. P. Shepherd
Abstract
We demonstrate the generation of high-energy, mid-IR, picosecond pulses in a high-harmonic-cavity optical parametric oscillator (OPO) that has a relatively compact cavity with a length that is a small fraction of that required to match the pump repetition rate. The OPO, based on an MgO-doped periodically poled LiNbO3 crystal, is pumped by a fiber master-oscillator-power-amplifier system employing direct amplification and delivering 11-μJ, 150-ps pulses at 1035 nm. For a 1.554-m-long OPO cavity, resonating near-infrared signal pulses with a repetition rate that is the 193rd harmonic of the 1-MHz pump are demonstrated. The mid-infrared idler output pulses, tunable from 2300 nm to 3500 nm, are generated at a 1-MHz repetition rate and have energies as high as 1.5 μJ.
High average power parametric wavelength conversion at 3.31–3.48 µm in MgO:PPLN
R. T. Murray, T. H. Runcorn, S. Guha, and J. R. Taylor
Abstract
We present results of high average power mid-infrared (mid-IR) generation employing synchronized nanosecond pulsed ytterbium and erbium fiber amplifier systems using periodically poled lithium niobate. We generate greater than 6 W of mid-IR radiation tunable in wavelength between 3.31–3.48 µm, at power conversion efficiencies exceeding 75%, with near diffraction limited beam quality (M2 = 1.4). Numerical modeling is used to verify the experimental results in differing pump depletion regimes.
Femtosecond OPO based on MgO:PPLN synchronously pumped by a 532nm fiber laser
Jianjun Cao, Dongyi Shen2 Yuanlin Zheng, Yaming Feng, Yan Kong and Wenjie Wan
Abstract
With the rapid progress in fiber technologies, femtosecond fiber lasers, which are compact, cost-effective and stable, have been developed and are commercially available. Studies of optical parametric oscillators (OPOs) pumped by this type of laser are demanding. Here we report a femtosecond optical parametric oscillator (OPO) at 79.6 MHz repetition rate based on MgO-doped periodically poled LiNbO3 (MgO:PPLN), synchronously pumped by the integrated second harmonic radiation of a femtosecond fiber laser at 532 nm. The signal delivered by the single resonant OPO is continuously tunable from 757 to 797 nm by tuning the crystal temperature in a poling period of 7.7 µm. The output signal shows good beam quality in TEM00 mode profile with pulse duration of 206 fs at 771 nm. Maximum output signal power of 71 mW is obtained for a pump power of 763 mW and a low pumping threshold of 210 mW is measured. Moreover, grating tuning and cavity length tuning of the signal wavelength are also investigated.
10W, high repetition rate, 775 nm fiber laser with high resolution pulse shaping, and on-demand pulse to pulse switching capability, for bioinstrumentation
Louis Desbiens, Vincent Roy, Michel Jacob, Yves Taillon
Abstract
Advances in the research fields of biological, biophysical and biochemistry rely on the development of novel, flexible, powerful and reliable laser sources in the visible – NIR part of the spectrum. Optical excitation in the 750-800 nm region, with flexible pulsed formats, can be advantageous in applications such as confocal fluorescence microscopy, STED, FLIM microscopy, photoluminescence spectroscopy, laser photocoagulation and time-resolved spectroscopy. Finely tailored pulse formatting can indeed provide significant enhancement in many of those techniques by optimizing the temporal distribution of the optical excitation with respect to the specific characteristics of the fluorophore of interest such as its excited-state lifetime for example. With those considerations we have developed a fiber laser source that combines a 1550 nm pulse-shaped MOPA system, offering coarse temporal control resolution (1 ns), with a high frequency AWG module operating at close to 8 GHz, that drives an intensity modulator downstream of the directly modulated semiconductor seed diode of the MOPA system.
Simple approach to high-fidelity tunable narrow-band pulse generation
C. W. Ballmann, G. I. Petrov, and V. V. Yakovlev
Abstract
Tunable narrow-band short-pulse coherent emission can be generated by the optical parametric amplification of a seeded continuous wave (CW) laser. However, the residual CW pedestal can affect the accuracy of the optical measurements and the exact interpretation of the experimental data. We demonstrate a simple approach to removing the residual CW seed in a frequency tunable, seeded parametric amplification setup in the nanosecond regime by adding an additional parametric amplification stage which is seeded by an idler wave from the first stage. We validate this method by using a pump-probe experiment in an atomic vapor. Our results show the elimination of an atomic vapor hyperfine pumping signal after the CW pedestal has been removed.
Fast and simple characterization of a photon pair source
F. Bussières, J. A. Slater, N. Godbout, and W. Tittel
Abstract
We present an exact model of the detection statistics of a probabilistic source of photon pairs from which a fast, simple and precise method to measure the source’s brightness and photon channel transmissions is demonstrated. We measure such properties for a source based on spontaneous parametric downconversion in a periodically poled LiNbO3 crystal producing pairs at 810 and 1550 nm wavelengths. We further validate the model by comparing the predicted and measured values for the g(2)(0) of a heralded single photon source over a wide range of the brightness. Our model is of particular use for monitoring and tuning the brightness on demand as required for various quantum communication applications. We comment on its applicability to sources involving spectral and/or spatial filtering.
A picosecond near-infrared laser source based on a self-seeded optical parametric generator
P. K. Upputuri, H. Wang
Abstract
We report on the design and development of a new type of near-IR laser source. The source comprises of an optical parametric generator (OPG) and a second harmonic generator (SHG) pumped by an 80-MHz, 1064-nm, 7-ps Nd:YVO4 laser. The OPG is self-seeded with a fraction of its own signal output, which significantly enhances its conversion efficiency. The SHG doubles the frequency of OPG signal to produce a coherent output. The final output beam has a tunable wavelength near 800 nm, an average power of over 1 W, and a pulse duration around 5 ps. The M2-factor of the output beam can reach 1.1 after spatial filtering. With the new laser source, we have successfully demonstrated coherent anti-Stokes Raman scattering microscopy on 1 μm polystyrene beads, which shows that it has the potential to be a substitute for a picosecond optical parametric oscillator in certain microscopy or spectroscopy applications.
Stimulated Raman Scattering Microscopy with a Robust Fibre Laser Source
C. W. Freudiger, W. Yang, G. R. Holtom, N. Peyghambarian, X. S. Xie, and K. Q. Kieu
Abstract
Stimulated Raman Scattering microscopy allows label-free chemical imaging and has enabled exciting applications in biology, material science, and medicine. It provides a major advantage in imaging speed over spontaneous Raman scattering and has improved image contrast and spectral fidelity compared to coherent anti-Stokes Raman. Wider adoption of the technique has, however, been hindered by the need for a costly and environmentally sensitive tunable ultra-fast dual-wavelength source. We present the development of an optimized all-fibre laser system based on the optical synchronization of two picosecond power amplifiers. To circumvent the high-frequency laser noise intrinsic to amplified fibre lasers, we have further developed a high-speed noise cancellation system based on voltage-subtraction autobalanced detection. We demonstrate uncompromised imaging performance of our fibre-laser based stimulated Raman scattering microscope with shot-noise limited sensitivity and an imaging speed up to 1 frame/s.
Differential optical absorption spectroscopy lidar for mid-infrared gaseous measurements
S. Lambert-Girard, M. Allard, M. Piché, and F. Babin
Abstract
This work presents the proof of concept of a remote sensing system designed for the detection of molecular species such as gas pollutants via active differential optical absorption spectroscopy in the short- and mid-wavelength infrared. The system includes an optical parametric generator generating broad linewidth pulses tunable between 1.5 and 3.8 μm. A telescope coupled to a grating spectrograph and an in-house gated HgCdTe avalanche photodiode measures the whole return spectrum from each pulse. Experiments show simultaneous detection in atmospheric air and inside a cell of H2O and CO2 at 2 μm, and H2O and CH4 at 3.3 μm. The detection limits for CO2 and CH4 are 158 and 1 ppm·m, respectively. A new algorithm is also presented enabling the determination of concentrations when spectra include strong absorption features.
Broadband and tunable optical parametric generator for remote detection of gas molecules in the short and mid-infrared
S. Lambert-Girard, M. Allard, M. Piché, and F. Babin
Abstract
The development of a novel broadband and tunable optical parametric generator (OPG) is presented. The OPG properties are studied numerically and experimentally in order to optimize the generator’s use in a broadband spectroscopic LIDAR operating in the short and mid-infrared. This paper discusses trade-offs to be made on the properties of the pump, crystal, and seeding signal in order to optimize the pulse spectral density and divergence while enabling energy scaling. A seed with a large spectral bandwidth is shown to enhance the pulse-to-pulse stability and optimize the pulse spectral density. A numerical model shows excellent agreement with output power measurements; the model predicts that a pump having a large number of longitudinal modes improves conversion efficiency and pulse stability.
