ABSTRACT
High-power vortex light generated directly from lasers will help drive their applications in material processing, optical manipulation, levitation, particle acceleration, and communications, but limited power has been achieved to date. In this work, we demonstrate record vortex average power of 31.3 W directly from a laser, to the best of our knowledge, using an interferometric mode transforming output coupler to convert a fundamental mode Nd:YVO4 laser into a LG01 vortex output. The vortex laser was Q-switched with up to 600 kHz pulse rate with a high slope efficiency of 62.5% and an excellent LG01 modal purity of 95.2%. We further demonstrate > 30W laser power in a high quality HG10 mode by simple adjustment of the output coupler. Experimental investigations of varying output coupling transmission are compared with theory. This successful implementation of the interferometric output coupler in a high power system demonstrates the suitability of the mode transforming method for robust turn-key vortex lasers with high efficiency and high modal purity, with scalable power and pulse rate.
ABSTRACT
Generation of vortex beams directly from the laser source can be limited in power and efficiency, or to specific pump sources and gain media. Here, we propose a new high power and high efficiency vortex laser methodology with interferometric mode transformation as output coupling, which uses high power handling and low loss optics that have wavelength versatility. Experimental demonstration is made in a diode-pumped Nd:YVO4 laser using an imbalanced Sagnac interferometer as output coupler producing high quality vortex output beams (M2 = 2.07) with fully selectable control of handedness whilst the intracavity mode is maintained as a fundamental Gaussian. Vortex output power >3W is produced with only small reduction in efficiency compared to the equivalent TEM00 laser. Continuous variation of vortex output coupling transmission and the quality of the vortex is investigated experimentally showing good agreement with theory. This work reveals a new approach to high power structured laser radiation direct from the source through interferometric spatial mode transformations.
ABSTRACT
We present the investigation of diode-side-pumping of Alexandrite slab lasers in a range of designs using linear cavity and grazing-incidence bounce cavity configurations. An Alexandrite slab laser cavity with double-pass side pumping produces 23.4 mJ free-running energy at 100 Hz rate with slope efficiency ~40% with respect to absorbed pump energy. In a slab laser with single-bounce geometry output power of 12.2 W is produced, and in a double-bounce configuration 6.5 W multimode and 4.5 W output in TEM00 mode is produced. These first results of slab laser and amplifier designs in this paper highlight some of the potential strategies for power and energy scaling of Alexandrite using diode-side-pumped Alexandrite slab architectures with future availability of higher power red diode pumping.
ABSTRACT
We present the first study of Q-switched Alexandrite lasers under continuous-wave diode-pumping with operation up to 10 kHz repetition rates in TEM00, with spatial quality M2 1.15. With a pulsed-diode dual-end-pumped design, pulse energy is scaled to a record level of 3 mJ. We also demonstrate, for the first time, cavity-dumped Q-switching of diode-pumped Alexandrite lasers under continuous-wave and pulsed diode-pumping, up to 10 kHz. Pulse energy of 510 µJ is demonstrated with 3 ns pulse duration and 170 kW peak power, in TEM00 with M2 < 1.2. Second harmonic generation of the cavity-dumped Q-switched pulses was used to generate UV wavelength 379 nm with conversion efficiency of 47%.
ABSTRACT
We present an investigation of a versatile pulsed laser source using a low power, gain-switched diode laser with independently variable repetition rate and pulse duration to seed an ultra-high gain Nd:YVO4 bounce geometry amplifier system at 1064nm. Small-signal gain as high as 50dB was demonstrated in a bounce geometry pre-amplifier from just 24W pumping, with good preservation of TEM00 beam quality. The single amplifier is shown to be limited by amplified spontaneous emission. Study is made of further scaling with a second power amplifier, achieving average output power of ~14W for a pulsed diode seed input of 188µW. This investigation provides some guidelines for using the bounce amplifier to obtain flexible pulse amplification of low-power seed sources to reach scientifically and commercially useful power levels.
ABSTRACT
A novel technique for obtaining enhanced control of pulsing parameters in a laser is described and implemented for the first time in a 1.1%Nd:YVO4 bounce geometry laser. The method uses a secondary laser cavity to control the gain in a Q-switched primary laser cavity and has enabled clean single-pulse Q-switched operation to be obtained across a repetition rate range of 1-800 kHz, where previously laser breakthrough had occurred below 150 kHz. Control of the pulse energy from the Q-switched laser is also demonstrated at a fixed repetition rate of 100 kHz by this technique.
ABSTRACT
This paper presents the highest average power passively Q-switched Nd:vanadate laser, to the best of our knowledge. A maximum average output power greater than 11 W was demonstrated using a Nd:YVO4 bounce geometry laser operating at 1064 nm in TEM00 mode, with a spatially stigmatic design. Pulse energies greater than 58 µJ and peak powers in excess of 1.9 kW were obtained; the maximum repetition rate recorded was 190 kHz, close to the upper limit achievable with Cr4+:YAG saturable absorbers.
Subject(s)
Lasers, Solid-State , Equipment Design , Equipment Failure AnalysisABSTRACT
We present the investigation of nonlinear mirror modelocking (NLM) of a bounce amplifier laser. This technique, a potential rival to SESAM modelocking, uses a nonlinear crystal and a dichroic mirror to passively modelock a Nd:GdVO(4) slab bounce amplifier operating at 1063nm. At 11.3W, we present the highest power achieved using the NLM technique, using type-II phase-matched KTP, with a pulse duration of 57ps. Using type-I phase-matched BiBO, modelocking was achieved with a shorter pulse duration of 5.7ps at an average power of 7.1W.
ABSTRACT
In this Letter, a first (to our knowledge) demonstration of phase conjugate self-organized coherent beam combination is reported. A demonstration involving combination of two self-adaptive gain grating holographic laser resonators is presented. Output powers of up to 27 W, with a combination efficiency of 94%, are demonstrated. This technique coherently combines individual phase conjugate laser modules, which do not have predefined spectral or spatial modes. This removes the problem of finding shared resonator modes, which should allow coherent beam combination of much larger laser arrays than standard self-organized coherent beam combination.
ABSTRACT
We demonstrate the compact high-power scaling of bounce geometry lasers with a new dual-pumped folded amplifier design. A Q-switched laser oscillator built with this amplifier is shown to produce over 30 W of average power from 80 W of pump power at up to 600 kHz repetition rate. In a master-oscillator power-amplifier (MOPA) configuration using the dual-pumped amplifier, we demonstrate over 100 W of output power from 250 W of pump power. We also demonstrate very high repetition rate Q-switching (1.7 MHz) of the master oscillator.
Subject(s)
Computer-Aided Design , Lasers, Solid-State , Equipment Design , Equipment Failure Analysis , Miniaturization , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
We present investigations into high-power scaling of solid-state amplified spontaneous emission (ASE) laser sources by use of two high-gain (~10(4)) Nd:YVO(4) bounce amplifiers. The sources deliver high power with a high-quality spatial output, but unlike a laser they have a high misalignment tolerance and do not require a precisely aligned cavity. In one system with two amplifiers, we demonstrate an ASE source with 24.5W of output power with good spatial quality, M(2)<2.5 in the horizontal and M(2)<1.2 in the vertical. In a more sophisticated setup, the two amplifiers are arranged in a loop configuration producing 30W of ASE output with near-diffraction-limited spatial quality, with M(2)<1.3 in the horizontal and M(2)<1.2 in the vertical, at an ~38% optical-to-optical conversion efficiency.
ABSTRACT
High efficiency and high power laser operation of highly-doped 2at.% crystalline Nd:YAG at 1.3microm is demonstrated in a diode-side pumped bounce amplifier configuration. A linearly polarized output power of 16.7W is obtained representing the highest power at 1.3microm achieved to date, to our knowledge, in a highly doped crystalline Nd:YAG laser. The system could deliver over 9W average output power in Q-switched operation with repetition rates from 20 - 160kHz. With quasi-continuous wave diode pumping 5.5mJ pulses at 100Hz repetition rate were achieved as well as 50ns pulses in Q-switched operation.
ABSTRACT
In this paper we present the first operation and power scaling of a modelocked Nd:YVO4 bounce laser oscillator at 1064 nm. We obtain up to 16.7 W of average output power from 38 W of pump power, in a continuous-wave modelocked pulse train with 30 ps pulses at a repetition rate of 78 MHz. We then use a Master Oscillator Power Amplifier (MOPA) configuration utilising another bounce amplifier, to achieve 60 W of modelocked output power.
ABSTRACT
An investigation is made into a quasi-CW (QCW) diode-pumped holographic adaptive laser utilising an ultra high gain (approximately 10(4)) Nd:YVO(4) bounce amplifier. The laser produces pulses at 1064 nm with energy approximately 0.6 mJ, duration <3 ns and peak power approximately 200 kW, with high stability, via self-Q-switching effects due to the transient dynamics of the writing and replay of the gain hologram for each pump pulse. The system produces a near-diffraction-limited output with M(2)<1.3 and operates with a single longitudinal mode. In a further adaptive laser configuration, the output was amplified to obtain pulses of approximately 5.6 mJ energy, approximately 7 ns duration and approximately 1 MW peak power. The output spatial quality is also M(2)<1.3 with SLM operation. Up to 2.9 mJ pulse energy of frequency doubled green (532 nm) radiation is obtained, using an LBO crystal, representing approximately 61% conversion efficiency. This work shows that QCW diode-pumped self-adaptive holographic lasers can provide a useful source of high peak power, short duration pulses with excellent spatial quality and narrow linewidth spectrum.
ABSTRACT
An investigation is made into the performance of a high power solid-state amplified spontaneous emission (ASE) source with near-diffraction-limited beam quality. The radiation from this ASE source has high spatial quality and power, but unlike a laser it has a high misalignment tolerance and does not require a precisely aligned cavity. The source is based on a diode-pumped Nd:YVO4 laser crystal in a bounce amplifier geometry with a uniquely ultra-high gain (~104-105). Double-pass ASE radiation with high power levels (>6W) is achieved in a near-diffraction-limited spatial quality. We further demonstrate that the double-pass ASE source also displays high spatial selectivity and capability to compensate for a phase diffuser, inserted in the double-pass arm, with only a small degradation in beam quality and power.
ABSTRACT
We describe, for the first time to our knowledge, the use of a saturable laser gain medium to implement an adaptive gain interferometer for performing optical metrology with speckle-distorted beams. We show that interferometric formation and replay of a saturable gain hologram permit coherent extraction of fast vibrational information about an object in real time and removal of slowly varying spatial distortion. An experimental characterization of the frequency response of the adaptive gain interferometer is made by use of a diode-pumped solid-state laser amplifier, and a new theoretical formulation of the gain interferometer is also developed for the first reported time.
ABSTRACT
We present, for what we believe is the first time, results of continuous-wave diode-pumping of a Nd:YVO (4) laser with an adaptive gain-grating resonator. The system is shown to produce more than a 7-W output in a TEM>(00) single longitudinal mode with a laser beam propagation parameter M(2) of <1.3 and <1.1 in the x and y axes, respectively. We demonstrate the self-adaptive abilities of the resonator by spatial correction of an intracavity aberrator for both injected and self-starting versions of the cavity.
ABSTRACT
Self-starting operation of a self-conjugating loop oscillator is achieved, for the first time to our knowledge, by use of an optically induced thermal hologram in a nonsaturable absorbing medium. Self-Q-switched single-longitudinal-mode pulses of 12-ns duration are obtained in a near-diffraction-limited spatial mode and with an output energy of >250 mJ . Good correction of intracavity phase distortions is obtained, as well as good extraction efficiency in the laser mode volume. It is shown that one has to set an additional nonreciprocal phase-shift element in the loop to ensure resonant operation of the system.
ABSTRACT
High-phase-conjugate reflectivities of >800% have been achieved through degenerate four-wave mixing in a cw diode-side-pumped Nd:YVO(4) amplifier. Reflectivity curves are shown as a function of input pump-beam intensity for three values of small-signal amplifier gain, and comparison is made with a numerical simulation.
ABSTRACT
We demonstrate, for the first time to our knowledge, operation of a holographic laser oscillator that uses laser-pumped Ti:sapphire (Ti(3+) : Al(2)O(3)) as the gain medium. The device is self-starting and self-adaptive by virtue of spontaneous gain-grating formation. We present experimental results of the system that include gain-switched pulses of 25-60-ns duration in a TEM(00) mode and as much as 11 mJ of output energy from a plane output coupler and 47 mJ from an intracavity polarizer port.
