A Q-swicthed all-solid-state single-longitudinal-mode laser with adjustable pulse-width and high repetition rate

A single-longitudinal-mode (SLM) laser-diode pumped Nd: YAG laser with adjustable pulse width is developed by using the techniques of pre-lasing and changing polarization of birefingent crystal. The Q-switching voltage is triggered by the peak of the pre-lasing pulse to achieve the higher stability of output pulse energy. The output energy of more than 1 mJ is obtained with output energy stability of 3% (rms) at 100 Hz. The pulse-width can be adjusted from 30 ns to 300 ns by changing the Q-switching voltage. The probability of putting out single-longitudinal-mode pulses is almost 100%. The laser can be run over four hours continually without mode hopping.

133-W pulsed fiber amplifier with large-mode-area fiber

A master-oscillator fiber power amplifier (MOPA) system with a 4-m-long Yb3+-doped homemade large mode area (LMA) double-clad fiber is reported. The system emits up to 133.8 W of amplified radiation at a wavelength of 1064 nm and a repetition rate of 100 kHz, limited only by the available pump power. Peak power of 300 kW at 20 kHz with a pulse duration of 15 ns is obtained. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Mode properties of off-axis one-sided hybrid resonator for novel high average power dual-slab laser

A novel dual-slab laser with off-axis one-sided hybrid resonator is presented. The mode properties of the hybrid resonator are calculated using a fast Fourier transform method (FFT). The influence of wavefront distoration on the output beam quality is considered. Results indicate that the novel dual-slab laser is better than the normal dual-slab laser with off-axis one-sided hybrid resonator.

Quasi-self-imaging planar waveguide lasers with high-power single-mode output

We describe high-power planar waveguide laser which can achieve single-mode output from a multi-mode structure. The planar waveguide is constructed with incomplete self-imaging properties, by which the coupling loss of each guided mode can be discriminated. Thermal lens effects are evaluated for single-mode operation of such high-power diode-pumped solid-state lasers. (c) 2005 Elsevier B.V. All rights reserved.

Transverse mode formation in longitudinally pumped miniature slab lasers

The formation of transverse modes in longitudinally pumped miniature slab lasers is investigated theoretically and experimentally. The longitudinally non-uniform gain-guiding is studied by expanding the electric field into the Hermite-Gaussian functions that satisfy boundary conditions of the resonator. Non-Gaussian transversal beam profiles in the near field are found and the beam diameter is reduced when the pump spot becomes smaller. The experimental observation agrees with the theoretical calculation.

Propagation of flat-topped beams

The propagation of flat-topped beams passing through paraxial ABCD optical system is investigated based on the propagation formulas of Gaussian beam. The focal shift of focused coherent flat-topped beam is also studied in detail. Analytical expressions of the M-2 factor and the far-field intensity distribution for flat-topped beams are derived on the basis of second-order moments. (C) 2007 Elsevier Ltd. All rights reserved.

High power single transverse mode operation of a tapered large-mode-area fiber laser

To get high output power with good beam quality, a tapered section is introduced to large-mode-area (LMA) Yb-doped fiber laser. Output characteristics of the fiber laser without tapered section and with tapered section are compared experimentally. When the launched pump power is 119.1 W, 77.9 W with M-2 3.08 and 56.4 W with M-2 1.14 can be obtained, respectively. The corresponding slope efficiencies are 71.8% and 54.1%, respectively. Although output power of the tapered fiber laser has 30.6% penalty, brightness of it is as much as 5.28 times of the fiber laser without tapered section. Moreover, spectra of them are measured. It is found that tapered section makes lasing wavelength of the fiber laser shorter. (c) 2007 Elsevier B.V. All rights reserved.

Study of crystal structure and phase transition studies in perovskite-type oxides using powder-diffraction techniques and symmetry-mode analysis.

251 p.

Low-loss planar and stripe waveguides in Nd3+-doped silicate glass produced by oxygen-ion implantation

We report on the fabrication and characterization of low-loss planar and stripe waveguides in a Nd3+-doped glass by 6 MeV oxygen-ion implantation at a dose of 1x10(15) ions/cm(2). The dark mode spectroscopy of the planar waveguide was measured using a prism coupling arrangement. The refractive index profile of the planar waveguide was reconstructed from a code based on the reflectivity calculation method. The results indicate that a refractive index enhanced region as well as an optical barrier have been created after the ion beam processing. The near-field mode profiles of the stripe waveguide were obtained by an end-fire coupling arrangement, by which three quasitransverse electric modes were observed. After annealing, the propagation losses of the planar and stripe waveguides were reduced to be similar to 0.5 and similar to 1.8 dB/cm, respectively. (c) 2007 American Institute of Physics.

Ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass produced by He+ ion implantation combined with Ar+ ion beam etching

This paper reports on the fabrication and characterization of a ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass. The He+ ion implantation (at energy of 2.8 MeV) is first applied onto the sample to produce a planar waveguide substrate, and then Ar+ ion beam etching (at energy of 500 eV) is carried out to construct rib stripes on the sample surface that has been deposited by a specially designed photoresist mask. According to a reconstructed refractive index profile of the waveguide cross section, the modal distribution of the waveguide is simulated by applying a computer code based on the beam propagation method, which shows reasonable agreement with the experimentally observed waveguide mode by using the end-face coupling method. Simulation of the incident He ions at 2.8 MeV penetrating into the Er3+/Yb3+ co-doped phosphate glass substrate is also performed to provide helpful information on waveguide formation.

Low loss waveguide in Nd3+-doped silicate glass fabricated by carbon ion implantation

Low loss index enhanced planar waveguides in Nd3+-doped silicate glass were fabricated by 3.0 MeV C+ ion implantation. The enhancement of the refractive index confined the light propagating in the waveguide. The prism-coupling method was used to measure dark modes in the waveguide. The effective refractive indices of the waveguide were obtained based on the dark modes. The moving fiber method was applied to measure the waveguide propagation loss. Loss measured in non-annealed samples is about 0.6 dB/cm. And the waveguide mode optical near-field output at 633 nm was presented. (c) 2005 Elsevier B.V. All rights reserved.

Property studies of optical waveguide formed by 6.0 MeV carbon ion implantation into Nd : silicate glass

Nd:silicate glass was implanted at room temperature by 6.0 MeV C3+ ions with a dose of 2.0 x 10(15) ions cm(-2). A waveguide with thickness of about 6.3 mu m was formed. The prism-coupling method was used to observe the dark modes of the waveguide at 633 nm and 1539 nm, respectively. There are three dark modes at 633 nm, of which one is the enhanced-index mode. The propagation loss of the enhanced-index mode in the waveguide measured at 633 nm is 0.42 dB cm(-1) after annealing at 217 degrees C for 35 min. The reflectivity calculation method was applied to simulate the refractive index profiles in the waveguide. The mode optical near-field output at 633 nm was presented.