Flavien Liegeois

High-average-power second-harmonic generation from periodically poled silica fibers

The generation of 236 mW of second-harmonic power in a 32-cm-long periodically poled silica fiber, corresponding to an average conversion efficiency of 15.2+/-0.5%, is reported. This represents the highest normalized second-harmonic conversion and the highest average second-harmonic power ever reported for a periodically poled silica fiber, to our knowledge. The enhancement is attributed to an improved design of the specialty twin-hole fiber and the extension of the nonlinear interaction length.

Wavelength-switchable single-frequency erbium-doped fiber ring laser

We demonstrate a single-frequency and wavelength-switchable fiber ring laser obtained by a Lyot filter used in combination with a sampled fiber Bragg grating and a saturable absorber. The operating wavelength of the laser can be tuned, with a constant 0.8-nm step, in the range 1552.6-1555.8 nm. The tuning mechanism works on the rotation of the polarization of Lyot filter input signal. The structure of the laser is very simple regarding its characteristics: an output power of 6 dBm, with a signal-to-noise ratio higher than 60 dB and a spectral linewidth of 8 kHz.

High-power ultrashort fiber laser for solar cells micromachining

We report on a high-power ultra-short fiber laser for thin film solar cells micromachining. The laser is based on Chirped Pulse Amplification (CPA) scheme. The pulses are stretched to hundreds of picoseconds prior to amplification and can be compressed down to picosecond at high energy. The repetition rate is adjustable from 100 kHz to 1 MHz and the optical average output power is close to 13 W (before compression). The whole setup is fully fibred, except the compressor achieved with bulk gratings, resulting on a compact and reliable solution for cold ablation.

All Fibre High repetition rate, High Power Picosecond Laser and UV generation

We report on a 93W, 1.1µJ, 83MHz, 35ps MOPA fibre laser based on an Yb mode-locked fibre oscillator and a rod-type LMA amplifier. This configuration can generate up to 20W at 343nm and we demonstrated over 2W at 257nm.

236mW average second-harmonic power generated from periodically poled silica fibres

Thermally poled silica fibres are an attractive all-fibre solution to frequency conversion of high power fibre lasers. In comparison to nonlinear crystals, they offer inherently lower insertion losses, higher optical damage threshold, greater stability and ruggedness intrinsic to all-fibre solutions. Moreover, the relatively low second-order-nonlinearity (0.1–0.2pm/V) can be compensated by extending the length of the periodically poled fibre.

Pulsed high-peak-power and single-frequency fibre laser design for LIDAR aircraft safety application

Laser wind velocimeters work by monitoring the Doppler shift induced on the backscattered light by aerosols that are present in the air. Recently there has been a growing interest in the scientific community for developing systems operating at wavelengths near 1.5 μm and based on all-fibre lasers configuration. In this paper, we propose a new all-fibre laser source that is suitable for Doppler velocimetry in aircraft safety applications. The all-fibre laser has been specifically conceived for aircraft safety application. Our prototype has a conveniently narrow linewidth (9 kHz) and is modulated and amplified through an all fibre Master Oscillator Power Amplifier (MOPA) configuration. According to the measurements, we performed the final characteristics of the laser consist in a maximum peak power of 2.7 kW and an energy of 27 μJ energy per pulses of 10 ns at 30 kHz repetition rate. The only limiting factor of these performances is the Stimulated Brillouin Scattering.

Single-Mode Ring Fiber Laser with Longitudinal Mach-Zehnder Mode Filter

A novel single-longitudinal-mode erbium doped ring fiber laser with Mach-Zehnder mode filter is proposed. The output power is 15 dBm at 1547 nm with a 50-dB side-mode suppression ratio and a 13-kHz linewidth.

Efficient high-power narrow-linewidth all-fibred linearly polarized ytterbium laser source

We report on experimental results on a high power, all-fibred, linearly polarized, mode-locked laser at 1.03 μm. The laser generates pulses of 40 ps wide at a repetition rate of 52 MHz, exhibiting 12 kW peak power. Dispersion in optical fibres is controlled to obtain both high power and narrow spectral linewidth. The average output power reached is 25 W with a spectral linewidth of 380 pm and a near diffraction limit beam (M2 < 1.2). This laser is an ideal candidate for applications like IR spectroscopy, where high peak power and narrow linewidth are required for subsequent wavelength conversion.

All fiber high energy, high power picosecond laser

We report on 83W, 14μJ, 5.9MHz, 30ps MOPA fiber laser based on an Yb modelocked fiber oscillator and a rod-type LMA amplifier. By frequency tripling, this configuration can generate up to 20W of UV.

Pulsed 1.55μm all-fiber laser combining high energy, ultranarrow linewidth and optimal spatial beam quality

In this letter, we report on the study of a new all-fiber laser source suitable for coherent Doppler LIDAR use in the eyesafe domain. The laser consists on a MOPA configuration where the Master Oscillator is a modulated ultranarrow (< 8 kHz) fiber laser. The optical amplifiers are also all-fibered and make use of a new Large Mode Area (LMA) index pedestal fiber that is very effective in limiting the non-linear effects without quality degradation of the laser beam. The amplified pulses have a maximum energy of 0.15 mJ for a duration of 340 ns at a repetition rate of 15 kHz. The average output power of the laser is 2.5 W, free of Stimulated Brillouin Scattering and with a measured M2 = 1.3.