Simon Boivinet

All-Fiber 1- \(\mu \) m PM Mode-Lock Laser Delivering Picosecond Pulses at Sub-MHz Repetition Rate

We report an all-fiber passively mode-locked laser at 1030 nm. The principle of this ultrafast laser is based on nonlinear polarization evolution occurring in a long span of birefringent fiber spliced between a polarizer and a Faraday mirror. This configuration supports a large variety of pulsed regimes: noise-like, multiple pulses, burst, and single pulse mode-lock operation. In the single pulse mode-lock regime, the pulse duration is ~ 17.8 ps at a low repetition rate of 948 kHz. The spectral bandwidth is ~ 2.2 nm, the pulse energy is 68 pJ, and the polarization extinction ratio is estimated to 15 dB.

3.3 MHz repetition rate all-fiber laser oscillator mode-locked by polarization rotation in PM fiber

Ultra-fast lasers are highly advanced tools in various applications such as medicine, micromachining or spectroscopy. Nevertheless their use could be even broader if reliability, costs and compactness were improved. Different solutions exist for mode-locking a laser cavity and generating ultrashort pulses. Some drawbacks related to these mode-locking mechanisms are still present and limit the use of such laser systems. For example, non-linear polarisation evolution based mechanism leads to lasers for which pulsed operation is very sensitive to external parameters like temperature; despite of their efficiency, semiconductor saturable absorbers have limited lifetime compared to the other components in a fiber laser cavity. We investigate here another solution for mode-locking in order to circumvent some of the classical impairments of this technology.

High-energy picosecond hybrid fiber/crystal laser for thin films solar cells micromachining

We report on an hybrid fiber/crystal ultra-short pulsed laser delivering high pulse energy and high peak power in the picosecond regime. The laser is composed of a mode-lock fiber oscillator, a pulse picker and subsequent fiber amplifiers. The last stage of the laser is a single pass Nd:YVO4 solid-state amplifier. We believe that this combination of both technologies is a very promising approach for making efficient, compact and low cost lasers compatible with industrial requirements.

Impact of chromatic dispersion and spectral filtering in an all-fiber mode-locked ytterbium laser

In this study, a polarization maintaining (PM) all-fiber laser oscillator passively mode locked at 1.03 μm is presented. The mode locking is achieved by nonlinear polarization evolution occurring along a long span of standard PM fiber (26 m) spliced between an off-axis polarizer and a Faraday rotator mirror. The influence of the total chromatic dispersion and intra-cavity spectral filtering on pulsed operation is studied. Two experimental configurations have been tested. The first configuration is an all normal dispersion cavity using a looped fibered circulator combined to a 1.5 nm filter used as an end cavity mirror. The second configuration used highly reflective chirped Fiber Bragg Grating (FBG) exhibiting different bandwidths (0.7 nm, 1.1 nm and 1.83 nm). The chromatic dispersion induced is +7.2 ps/nm for each FBG. Stable single-pulse mode locked operation has been demonstrated for each configuration. The study highlights however different mode-locking operations according to the intra-cavity spectral filtering and total chromatic dispersion of the cavity. For the first configuration, pulse duration is about 7 ps. According to the optical spectrum which has a FWHM of 2.2 nm, pulses may be compressed to subpicosecond durations with the help of a suited compressor like bulk gratings. Shortest pulses of 2.2 ps have been obtained at a repetition rate of 3.3 MHz with the second experimental configuration. To our knowledge, this is the smallest pulse duration delivered by a fully fibered mode locked laser operating at a repetition rate lower than 10 MHz without any external pulse compressor.

948 kHz repetition rate, picosecond pulse duration, all-PM 1.03 μm mode-locked fiber laser based on nonlinear polarization evolution

We present in this study a PM all-fiber laser oscillator passively mode-locked (ML) at 1.03 μm. The laser is based on Nonlinear Polarization Evolution (NPE) in polarization maintaining (PM) fibers. In order to obtain the mode-locking regime, a nonlinear reflective mirror including a fibered polarizer, a long fiber span and a fibered Faraday mirror (FM) is inserted in a Fabry-Perot laser cavity. In this work we explain the principles of operation of this original laser design that permits to generate ultrashort pulses at low repetition (lower that 1MHz) rate with a cavity length of 100 m of fiber. In this experiment, the measured pulse duration is about 6 ps. To our knowledge this is the first all-PM mode-locked laser based on the NPE with a cavity of 100m length fiber and a delivered pulse duration of few picosecondes. Furthermore, the different mode-locked regimes of the laser, i.e. multi-pulse, noise-like mode-locked and single pulse, are presented together with the ways of controlling the apparition of these regimes. When the single pulse mode-locking regime is achieved, the laser delivers linearly polarized pulses in a very stable way. Finally, this study includes numerical results which are obtained with the resolution of the NonLinear Schrodinger Equations (NLSE) with the Split-Step Fourier (SSF) algorithm. This modeling has led to the understanding of the different modes of operation of the laser. In particular, the influence of the peak power on the reflection of the nonlinear mirror and its operation are studied.

Ultra-fast ytterbium fiber laser operating at low repetition rate

We present a theoretical and experimental study on PM ultra-short fiber laser cavities operating at low repetition rate. The mode-locking operation in this study always relies on SEmicondutor Saturable Absorber Mirror (SESAM) and intracavity spectral filtering. Several experimental configurations have been tested and modeled. Repetition rates as low as 7.7 MHz with sub-picosecond pulse duration have been obtained. A longer cavity has also been modeled in order to determine if stable ultra-short pulsed operation would also possible at lower repetition rates.