Coherent combination of micropulse tapered amplifiers at 828 nm for direct-detection LIDAR applications.

We report on the design of a compact master oscillator power amplifier (MOPA) diode laser architecture at 828 nm suitable for direct-detection LIDARs, specifically applied to water vapor differential absorption LIDARs. Coherent beam combination of two pulsed high-brightness tapered amplifiers (1 µs, 10 kHz), seeded by a DBR laser diode, is demonstrated. The phase dynamics during the pulses have been thoroughly investigated. The main limitation to the CBC efficiency is quantified. The maximum combined pulse energy reaches 10.3 µJ with combining efficiency above 82% ± 5%.

Narrow line width operation of a 980 nm gain guided tapered diode laser bar.

We demonstrate two different schemes for the spectral narrowing of a 12 emitter 980 nm gain guided tapered diode laser bar. In the first scheme, a reflective grating has been used in a Littman Metcalf configuration and the wavelength of the laser emission could be narrowed down from more than 5.5 nm in the free running mode to 0.04 nm (FWHM) at an operating current of 30 A with an output power of 8 W. The spectrum was found to be tunable within a range of 16 nm. In the second scheme, a volume Bragg grating has been used to narrow the wavelength of the laser bar from over 5 nm to less than 0.2 nm with an output of 5 W at 20 A. To our knowledge, this is the first time spectral narrowing has been performed on a gain guided tapered diode laser bar. In the Littman Metcalf configuration, the spectral brightness has been increased by 86 times and in the volume Bragg grating cavity the spectral brightness has been improved over 18 times when compared to the free running operation. These schemes could be also extended for other wavelengths of interest in the future.

Coherent beam superposition of ten diode lasers with a Dammann grating.

We demonstrate the use of a binary diffractive optical element in a very simple setup to convert the multilobed beam from a low fill factor array of coherent laser diodes into a quasi-Gaussian beam. The phase profile of the grating is determined with a phase retrieval algorithm. Experimentally, the conversion efficiency reaches more than 44%. We also establish that this setup can be used to make an effective measurement of the coherency of the laser array.

Continuous-wave diode-pumped solid-state laser with an intracavity fiber Bragg grating.

We demonstrate the feasibility of a new concept of laser that benefits from both fiber and laser crystals: a cw diode-pumped solid-state laser with an intracavity fiber Bragg grating as the output coupler. The design of the laser cavity and the experimental demonstration are both described. Several applications are mentioned.

Self-compression and Raman soliton generation in a photonic crystal fiber of 100-fs pulses produced by a diode-pumped Yb-doped oscillator.

We present the use of a photonic crystal fiber to straightforwardly compress ultrashort pulses from a diode-pumped ytterbium laser emitting around 1 microm. 75-fs pulse generation and a large 1-1.3-microm tunability for sub-100-fs pulses is reported.