A. Minassian

High repetition rate Q-switching performance in transversely diode-pumped Nd doped mixed gadolinium yttrium vanadate bounce laser.

Up to 700 kHz high repetition active Q-switching was achieved with a pulse-width of < 40 ns by using a diode-side-pumped Nd:Gd_xY_1-xVO₄ bounce amplifier. The average output power of 17.5 W was obtained at a pump power of 41 W.

High repetition rate Q-switching of high power Nd:YVO4 slab laser

A high power, diode-side-pumped Nd:YVO4 laser with a grazing incidence cavity geometry was acousto-optically Qswitched at frequencies up to 500 kHz. In CW operation, the laser output power was 16.4 W at 30.5 W of diode pump, corresponding to optical conversion efficiency of 53.8%. In Q-switching operation, measurements were made of average output power, pulse duration, pulse energy and peak power as a function of Q-switching frequency. At 200 kHz repetition rate and pump power 30 W, the laser output had average power 15.9 W (optical conversion efficiency 53%), pulse duration 15 ns, pulse energy 80 lJ and peak power 5.3 kW. A numerical modeling of the Q-switched laser was performed and results compared with experimental data. 2003 Published by Elsevier Science B.V.

Powerful visible (530–770 nm) luminescence in Yb,Ho:GGG with IR diode pumping

Powerful visible luminescence in a Gadolinium Gallium Garnet (GGG) crystal, co-activated with Yb3+ (~15 at.%) and Ho3+ (~0.1 at.%) ions, is investigated under CW laser diode pumping (lambda = 938 and 976 nm). The main visible emission band is observed in the green with its peak at lambda ~540 nm) and measured to be about 10% with respect to Yb3+ IR luminescence (lambda ~1000 nm). Red (lambda ~650 nm) and near-IR (lambda ~755 nm) emission bands are also observed but are weaker (about 3-5%). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+ - Ho3+ stepwise up-conversion is the mechanism explaining the phenomenon. Ho3+ ions embedded in the crystal in small concentration are shown to form an effective reservoir for energy transferred from the excited Yb3+ subsystem and to be an efficient source of the visible emission.

High efficiency laser operation of 2 at.% doped crystalline Nd:YAG in a bounce geometry

High-efficiency high-power operation of 2 at.% crystalline Nd:YAG is demonstrated. CW output power of 46.1 W and slope efficiency of 60% are obtained, and 11 mJ pulses at 100 Hz with QCW-pumping are achieved with 12 ns Q-switched pulses.

Self-starting Ti:sapphire holographic laser oscillator.

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.

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. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

Laser operation at 1.3μm of 2at.% doped crystalline Nd:YAG in a bounce geometry

This paper reports for the first time high power laser operation in Czochralski grown 2at.% doped crystalline Nd:YAG at 1.3 μm by use of the bounce amplifier geometry. The 1.3 μm fundamental output from the laser was frequency doubled externally in an LBO second harmonic crystal to generate red light. Three different second harmonic frequencies could be observed at 659 nm, 669 nm and 664 nm.

Efficient continuous-wave generation in a self-organizing diode-pumped Nd:YVO 4 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 9.6 W of power and 32% optical efficiency is obtained. Spectral compositions and temporal dynamics are investigated as functions of diode-pumping power.

Power scaling of highly neodymium-doped YAG ceramic lasers with a bounce amplifier geometry.

High power operation of highly-doped ceramic Nd:YAG laser is demonstrated using a laser diode transversely-pumped bounce geometry. Using a 2% doped ceramic Nd:YAG amplifier, an output power of 45W was achieved with 158W diode pumping. The cavity configuration was optimized for TEM00 operation and a high spatial quality output (M2 >1.5) was obtained at an output power of 27W. A ceramic Nd:YAG laser with 4% doping was operated at over 1 watt of output power. These are the highest power levels achieved in ceramic Nd:YAG lasers at >1% doping level.

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. The powers of the beams involved in the resonator are compared with theory and are found to be in good agreement. Spectral and temporal behavior of the adaptive laser is investigated, and very interesting behavior is shown, including self-induced temporal modulation dynamics and a switching between a narrowband and a broad bandwidth of operation.