Widely-tunable synchronisation-free picosecond laser source for multimodal CARS, SHG, and two-photon microscopy
Duanyang Xu, Sijing Liang, Lin Xu, Konstantinos N. Bourdakos, Peter Johnson, James Read, Jonathan H. V. Price, Sumeet Mahajan, and David J. Richardson
Abstract
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, tunable, ultrafast yellow laser using cascaded second harmonic generation of mid-IR Cr2+:ZnS laser in MgO:PPLN crystals
Anirban Ghosh, Deepika Yadav, Ravi Kiran Saripalli, Goutam K. Samanta
Abstract
We report on efficient, two stage single-pass second harmonic generation of ultrafast Cr2+:ZnS laser with spectral bandwidth of 138 nm centered at ~2360 nm and pulse width of ~43 fs at a repetition rate of 80 MHz into tunable yellow radiation across 577 – 589 nm in multi-grating MgO:PPLN crystals. A maximum average output power ~940 mW at 589 nm wavelength with a single-pass conversion efficiency as high as 41% was achieved. The yellow radiation has a spectral bandwidth of 2 nm and pulse-width of ~913 fs in absence of any pulse compression with a time-bandwidth product of 1.58.
Efficient difference frequency generation for quantum frequency conversion in a multimode PPLN-waveguide
H. Huber, M. Walochnik, F. Elsen, B. Jungbluth, Peter Loosen
Abstract
Converting single photons from one wavelength to another is of fundamental interest for future quantum communication and computing. Using commercially available lasers and a multimode PPLN waveguide a DFG scheme was set up. Phase-matching was shown in the fundamental transverse mode of the waveguide for wavelengths between 851 nm and 862 nm. The setup is capable of converting up to 87% of photons from 856 nm to 1526 nm in transverse fundamental mode. Simulations were performed showing that the quantum conversion efficiency at 856 nm is representative for powers down to thousands of photons per second.
SPDC photon pairs using a spatially anti-symmetric pump beam in a ppLN ridge waveguide
Ramesh Kumar & Joyee Ghosh
Abstract
In this paper, we study the possible parametric down-conversion processes in a type II phase-matched, Lithium Niobate ridge waveguide, designed to generate photon pairs in the telecommunication range. A quantum analysis of spontaneous parametric down-conversion (SPDC), first, with a pulsed Gaussian pump beam and second, with a pulsed, spatially anti-symmetric Hermite-Gaussian HG (1,0) pump beam predict the possible down conversion processes in each case. In case of the former, degenerate photon pairs are emitted at 1550 nm with the highest efficiency in the fundamental waveguide mode. While, in case of the latter, non-degenerate photon pairs in different higher-order spatial modes are generated. The joint spectral amplitude (JSA) analysis of these processes, prove that the generated photons pairs having orthogonal polarizations are negatively correlated. With multiple degrees of freedom, like polarization and spatial modes, such photons can be further harnessed towards modal-entangled and hyper-entangled photons for quantum information applications. This study involving the JSA is one of the first kinds, especially, to show the possibility of photon pairs generated in different spatial modes and polarization, after being incident with a spatially anti-symmetric pump beam in a ridge waveguide scenario.
Yudi Wu, Sijing Liang, Qiang Fu, Lin Xu, and David J. Richardson
Abstract
A compact, mid-infrared, synchronously pumped, fiber-feedback optical parametric oscillator (OPO) based on periodically poled lithium niobate (PPLN) is developed. The OPO generates 1-MHz picosecond pulses with 1.24μJ pulse energy and 9.7kW peak power.
Toward industrial and fibered non-linear sum frequency generation devices
Alexis Mehlman, David Holleville, Michel Lours, Sébastien Bize, Ouali Acef, Aurélien Boutin, Karine Lepage, and Ludovic Fulop
Abstract
We report on the development of an all-fibered sum frequency generation device using a PPLN crystal. A 5-5.5Wcm conversion efficiency and an 80 coupling efficiency were reached, with a peak-to-peak residual power fluctuations under 2.
Near-Maximal Two-Photon Entanglement for Optical Quantum Communication at 2.1 um
Adetunmise C. Dada, Jędrzej Kaniewski, Corin Gawith, Martin Lavery, Robert H. Hadfield, Daniele Faccio, and Matteo Clerici.
Abstract
Owing to a reduced solar background and low propagation losses in the atmosphere, the 2- to 2.5-μm waveband is a promising candidate for daylight quantum communication. This spectral region also offers low losses and low dispersion in hollow-core fibers and in silicon waveguides. We demonstrate near-maximally entangled photon pairs at 2.1μm that could support device-independent quantum key distribution (DIQKD), assuming sufficiently high channel efficiencies. The state corresponds to a positive secure-key rate (0.254 bits/pair, with a quantum bit error rate of 3.8%) based on measurements in a laboratory setting with minimal channel loss and transmission distance. This is promising for the future implementation of DIQKD at 2.1μm.
All-fiber picosecond laser source based on nonlinear spectral compression
M. Rusu and O. G. Okhotnikov
Abstract
The authors report the realization of an all-fiber system emitting high-quality ultrashort powerful light pulses at 1060 nm. The oscillator-amplifier system is intended for compact visible light generation via frequency conversion. Optical nonlinearity in a fiber amplifier is employed to compress the spectrum of pulses negatively prechirped in a hollow core photonic bandgap fiber. Second-harmonic generation in a periodically poled crystal is demonstrated.
Blue light generated by intra-cavity frequency doubling of an edge-emitting diode laser with a periodically poled LiNbO3 crystal
K. Li, A. Yao, N. J. Copner, C. B. E. Gawith, I. G. Knight, H. Pfeiffer, and B. Musk
Abstract
We demonstrate for the first time to our knowledge intra-cavity frequency doubling (ICFD) of an edge-emitter diode laser using a 10 mm-long 5.0 μm periodically poled LiNbO3 (PPLN) crystal. An optical output power of 33 mW second harmonic blue light at 490.5 nm is generated at 1.0 A injection current, equivalent to an overall wall-plug efficiency of 1.8%. The measured M2 values of blue beam are 1.7 and 2.4 along the fast and slow axis.
Intra-cavity frequency doubling of an electrically pumped edge-emitting 980 nm laser diode with PPLN
K. Li, A. Yao, N. J. Copner, C. B. E. Gawith, I. G. Knight
Abstract
A novel intra-cavity frequency doubling of an electrically pumped edge-emitting laser diode was demonstrated for the first time to our knowledge. The experimental data agree well with the numerical results based on our model.
