Continuous-Wave Nd:YVO4 self-Raman lasers operating at 1109nm, 1158nm and 1231nm

Several continuous-wave Nd:YVO4 self-Raman lasers based on the primary and secondary Raman transitions of YVO4 (893cm−1 and 379cm−1 respectively) are reported in this paper. Laser outputs were obtained at a wavelength of 1109nm, 1158nm and 1231nm with maximum output powers of 1.0W, 700mW and 540mW respectively. The respective absorbed pump power to Raman output power conversion efficiencies were measured at 8.4%, 5.4%, and 5.4%

Dual Q-switched laser outputs from a single lasing medium using an intracavity MEMS micromirror array

An intracavity array of individually controlled microelectromechanical system scanning micromirrors was used to actively Q-switch a single side-pumped Nd:YAG gain medium. Two equal power independent laser outputs were simultaneously obtained by separate actuation of two adjacent micromirrors with a combined average output power of 125 mW. Pulse durations of 28 ns FWHM at 8.7 kHz repetition frequency and 34 ns FWHM at 7.9 kHz repetition frequency were observed for the two output beams with beam quality factors M2 of 1.2 and 1.1 and peak powers of 253 W and 232 W, respectively

Q-switched tunable solid-state laser using a MOEMS mirror

Simultaneous wavelength tuning and Q-switching of a Yb:KGW laser using a single, electrothermally actuated MOEMS mirror is reported for the first time. A 15.4 nm tuning range is achieved at 2.06 kHz pulse repetition frequency

Tunable Yb:KGW laser, CW or Q-switched, enabled by dual-axis tilt of a MOEMS mirror : KGW laser, CW or Q-switched, enabled by dual-axis tilt of a MOEMS mirror

The experimental proof-of-concept demonstration of an end-pumped Yb:KGW laser with tunable spectral and temporal output characteristics is reported. For the first time, tuning of both of these characteristics in a solid-state laser is achieved simultaneously using a single electrothermally-actuated MOEMS micromirror with controllable tilt angle in two dimensions. In continuous-wave mode, a wavelength tuning range of 22 nm with < 0.3 nm linewidth was achieved by using static MOEMS mirror tilt about one axis to select the intracavity wavelength dispersed by a prism. A wavelength tuning range of 15.3 nm with < 1.1 nm linewidth was achieved in Q-switched operation, by using simultaneous static tilt and resonant scanning of the MOEMS mirror about orthogonal axes. In this operational mode, a pulse repetition rate of 2.06 kHz was obtained with pulse durations varying from 460 ns to 740 ns over the addressable range of laser wavelengths

Range extension of a bimorph varifocal micromirror through actuation by a Peltier element

A bimorph varifocal micromirror actuated thermoelectrically by a Peltier element is reported. The single crystal silicon micromirror is 1.2 mm in diameter with a centered 1 mm diameter gold coating for broadband reflection. The actuation principle is capable of varying the micromirror temperature above and below the ambient temperature, which contributed to a 57% improvement in the addressable curvature range in comparison to previously reported electrothermal and optothermal actuation techniques for the device. Altering the device temperature from 10 C to 100 C provided a mirror surface radius of curvature variation from 19.2 mm to 30.9 mm respectively. The experimental characterization of the micromirror was used as a basis for accurate finite element modeling of the device and its actuation. Negligible optical aberrations are observed over the operating range, enabling effectively aberration-free imaging. Demonstration in an optical imaging system illustrated sharp imaging of objects over a focal plane variation of 212 mm

Wavelength tuning of a solid-state laser with a tilting mems micromirror

Wavelength tuning of a Yb:KGW solid-state laser is presented using an electrothermally actuated micromirror and a diffraction grating or dispersing prism. 27 nm and 7.5 nm tuning ranges are achieved using extracavity and intracavity configurations respectively

Spectral and temporal control of Q-switched solid-state lasers using intracavity MEMS

Active control of the spectral and temporal output characteristics of solid-state lasers through use of MEMS scanning micromirrors is presented. A side-pumped Nd:YAG laser with two intracavity scanning micromirrors, enabling Q-switching operation with controllable pulse duration and pulse-on-demand capabilities, is investigated. Changing the actuation signal of one micromirror allows a variation of the pulse duration between 370 ns and 1.06 μs at a pulse repetition frequency of 21.37 kHz and average output power of 50 mW. Pulse-on-demand lasing is enabled through actuation of the second micromirror. To our knowledge this is the first demonstration of the use of multiple intracavity MEMS devices as active tuning elements in a single solid-state laser cavity. Furthermore, we present the first demonstration of control over the output wavelength of a solid-state laser using a micromirror and a prism in an intracavity Littman configuration. A static tilt actuation of the micromirror resulted in tuning the output wavelength of an Yb:KGW laser from 1024 nm to 1031.5 nm, with FWHM bandwidths between 0.2 nm and 0.4 nm. These proof-of-principle demonstrations provide the first steps towards a miniaturized, flexible solid-state laser system with potential defense and industrial applications

1.6 W continuous-wave Raman laser using low-loss synthetic diamond

Low-birefringence (Δn<2x10−6), low-loss (absorption coefficient <0.006cm−1 at 1064nm), single-crystal, synthetic diamond has been exploited in a CW Raman laser. The diamond Raman laser was intracavity pumped within a Nd:YVO4 laser. At the Raman laser wavelength of 1240nm, CW output powers of 1.6W and a slope efficiency with respect to the absorbed diode-laser pump power (at 808nm) of ~18% were measured. In quasi-CW operation, maximum on-time output powers of 2.8W (slope efficiency ~24%) were observed, resulting in an absorbed diode-laser pump power to the Raman laser output power conversion efficiency of 13%

MEMS Q-switched solid-state lasers

This paper reports the incorporation of low-cost, scanning Micro-Electro-Mechanical Systems (MEMS) micromirrors as active Q-switch elements within a solid-state laser cavity. Active Q-switching can be achieved through the rapid scanning of an electro-static, comb-drive actuated micromirror [1]. The use of MEMS devices will allow prospects of miniaturisation of laser systems with lower fabrication costs and energy consumption than common laser Q-switch elements such as acousto-optic or electro-optic devices. To investigate this, a three-mirror, side-pumped Nd:YAG laser cavity (fig.1) incorporating a resonant MEMS micromirror as an active Q-switch element was constructed. The total optical scanning angle of the electrostatically-actuated micromirror was measured at 75⁰ with a mechanical resonance frequency of 7.905kHz. A gold layer was deposited on the micromirror surface to ensure laser conversion efficiency and reduce thermal build-up within the silicon device. However, this coating process led to a concave surface curvature measured at ROC=0.22m. The micromirror was aligned so that the optimum cavity alignment was normal to the mirror surface. Q-switched output beams were obtained in a dual spot pattern (fig.2) with pulse durations as short as 130ns and pulse energies of up to 3.2μJ. Each individual spot was emitted consecutively with a frequency equal to the mechanical resonance frequency of the micromirror. This is due to the bidirectional nature of the MEMS movement and the time delay (measured at ~400ns) between the pulse emission and the scanning through the optimum alignment position. Moreover, an average timing pulse-to-pulse jitter of ~15ns was measured and the beam quality factor of each beam was measured at M2 =1.1. We will present a full characterisation of the novel active Q-switching method as well as the initial steps towards the powerscaling of this technique

Continuous-wave Raman laser pumped within a semiconductor disk laser cavity

A KGd(WO4)(2) Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5: 6W of absorbed diode pump power, and output power up to 0.8W at 1143nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157nm