Transient pump-probe analysis of pump-induced lensing in laser amplifiers.

Understanding of pump-induced lensing in laser amplifiers is essential for the optimized design of high-power lasers with high spatial quality, but there is usually incomplete knowledge of the interplay between thermal and population induced lensing mechanisms, lensing under lasing and non-lasing conditions, and transient lensing effects under pulsed operation. This paper provides quantitative insight of pump-induced lensing effects by using experimental transient pump-probe measurements in an alexandrite laser amplifier end-pumped by a short pulse pump beam with Gaussian spatial intensity distribution. Lensing results are presented showing a large difference in lensing under both non-lasing and lasing conditions and distinction of the population lens and thermal lens contributions from their different response time.

High-energy acousto-optic Q-switched alexandrite laser with wavelength tunable fundamental and UV second harmonic generation.

We investigate high-energy mJ-class diode-pumped acousto-optic (AO) Q-switched alexandrite lasers with broad tunability at both the fundamental near-IR wavelength range and second harmonic generation (SHG) in the UV wavelength range. An AO Q-switched alexandrite laser with continuous-wave diode-pumping has been operated at up to 10 kHz and producing pulse energy of 700 µJ at repetition rate of 1 kHz. With pulsed double-pass diode-pumping, we demonstrate higher pulse energy of 2.

Temperature-tunable UV generation using an Alexandrite laser and PPLN waveguides.

We present a simple and novel technique for achieving ultra-violet (UV) wavelength-tunable laser operation in the continuous-wave regime. Wavelength tunable operation in the near infrared is obtained from a compact two-mirror Alexandrite laser cavity by temperature tuning of the laser crystal. Second-harmonic-generation to the UV is then achieved at 376-379 nm and 384-386 nm by temperature tuning of a periodically-poled lithium-niobate (PPLN) waveguide.

Alexandrite lasers with blue-diode-pumping.

The availability of high-power and high-brightness blue diode lasers makes them attractive as low-cost pump sources for broadly tunable Alexandrite lasers. In this paper we investigate the performance of an Alexandrite laser pumped by a high-power fiber-delivered blue diode module. Output power 1.

Sampling a vortex from a Gaussian beam using a wedge-plate shearing interferometer.

Many vortex-generation techniques have been developed to address a range of potential applications, exploiting their unique amplitude and phase profiles and their possession of orbital angular momentum. In this work, we present what may be the simplest method of vortex beam generation, requiring only a wedged optic: the wedge-plate shearing interferometer (WPSI). We show that the WPSI can reflect a first order Laguerre-Gaussian vortex beam () with a theoretical purity of >99 from an input fundamental Gaussian beam, with 98% purity experimentally demonstrated.

Pump-induced lensing effects in diode pumped Alexandrite lasers.

It is essential to understand the pump-induced lensing and aberration effects in solid-state lasers, such as Alexandrite, since these set limits on laser power scaling whilst maintaining high spatial TEM beam quality. In this work, we present direct wavefront measurements of pump-induced lensing and spherical aberration using a Shack-Hartmann wavefront sensor, for the first time, in a diode-pumped Alexandrite laser, and under both non-lasing and lasing conditions. The lens dioptric power is found to be weakly sub-linear with respect to the absorbed pump power, and under lasing, the lensing power is observed to decrease to 60 % of its non-lasing value.

Tunable, dual wavelength and self-Q-switched Alexandrite laser using crystal birefringence control.

We present a red-diode-pumped Alexandrite laser with continuous wavelength tunability, dual wavelength and self-Q-switching in an ultra-compact resonator containing only the gain medium. Wavelength tuning is obtained by varying the geometrical path length and birefringence by tilting a Brewster-cut Alexandrite crystal. Two crystals from independent suppliers are used to demonstrate and compare the performance.

Unidirectional single-frequency operation of a continuous-wave Alexandrite ring laser with wavelength tunability.

High resolution spectroscopy, metrology and quantum technologies (e.g. trapping and cooling) require precision laser sources with narrow linewidth and wavelength tunability.

Vortex laser from anti-resonant ring coupled cavities.

Optical vortex Laguerre-Gaussian (LGl) modes have wide-ranging applications due to their annular spatial form and orbital angular momentum. Their direct generation from a laser is attractive, due to the pure and high-power modes possible; however, previous demonstrations have had limited ranges of applicability. Here, we propose and implement direct LGl vortex mode generation with an anti-resonant ring (ARR) coupled laser cavity geometry, where the gain medium inside the ARR is shared between two laser cavities.

Temperature effects on tunable cw Alexandrite lasers under diode end-pumping.

Diode pumped Alexandrite is a promising route to high power, efficient and inexpensive lasers with a broad (701 nm to 858 nm) gain bandwidth; however, there are challenges with its complex laser dynamics. We present an analytical model applied to experimental red diode end-pumped Alexandrite lasers, which enabled a record 54 % slope efficiency with an output power of 1.2 W.

High efficiency >26 W diode end-pumped Alexandrite laser.

We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating.

Over 40-watt diffraction-limited Q-switched output from neodymium-doped YAG ceramic bounce amplifiers.

High power operation of high repetition Q-switched ceramic Nd:YAG laser is demonstrated using a master-oscillator power amplifier with a transversely-pumped bounce geometry. The laser system produced >40W high spatial quality output (M(2) <1.3) at a pulse repetition frequency of >100kHz.

Efficient continuous-wave generation in a self-organizing diode-pumped Nd:YVO4 laser with a reciprocal dynamic holographic cavity.

A diode-pumped Nd:YVO4 laser is demonstrated that has a reciprocal self-intersecting loop cavity with self-organization by formation of a dynamic holographic grating induced by the generating beam. Continuous-wave high spatial quality generation (M2 < 1.2) with 9.

Unidirectional single-frequency operation of a Nd:YVO4 ring laser with and without a Faraday element.

We demonstrate high-performance unidirectional and single-frequency ring-laser operation based on a diode-side-pumped Nd:YVO4 bounce amplifier, obtained in a ring system both with and without a Faraday rotating element. Ring-laser operation with intracavity Faraday unidirectional element produces 15-W cw output in a TEM00 and single-longitudinal mode with beam propagation parameter M2 < 1.1 with 35-W diode pumping.

Efficient operation of a solid-state adaptive laser oscillator.

We present the results of a cw diode-pumped Nd:YVO4 laser oscillator based on a self-starting adaptive gain-grating resonator. Adaptive laser operation has been demonstrated with 12-W output for 37 W of diode pumping, producing a TEM00 mode that compensates for thermal aberrations. The issue of the finite aperture of the amplifier is discussed, and a design that incorporates an intracavity lens is used to improve the collection efficiency with severe thermal lensing at high pump powers.