Construction of the refractive index profiles for few-mode planar optical waveguides

We present a nondestructive technique to predict the refractive index profiles of isotropic planar waveguides, on which a thin gold film is deposited to as the cladding. The negative dielectric constant of the metal results in significant differences of effective indices between TE and TM modes. The two polarized modes and a surface plasmon resonance (SPR) with abundant information of the surface index can be used to construct the refractive index profiles of single-mode and two-mode waveguides at a fixed wavelength. (c) 2005 Elsevier B.V. All rights reserved.

Design and analysis of a kind of large flattened mode optical fibre

In this paper, a refractive index pro. le design enabling us to obtain a. at modal field around the fibre centre is investigated. The theoretical approach for designing such multilayer large flattened mode (LFM) optical fibres is presented. A comparison is made between the properties of a three-layer LFM structure and a standard step-index pro. le with the same core size. The obtained results indicate that the effective area of the LFM fibre is about twice as large as that of the standard step-index fibre, but the LFM fibre has less effective ability to filter out the higher order modes than the standard step-index fibre with the same bending radius.

Single mode Er-doped pi-phase-shifted distributed feedback fibre grating laser

A novel method incorporating the shielded method and the post-processing method has been proposed to fabricate the pi-phase-shilted fibre grating. Then an Er-doped pi-phase-shifted distributed feedback fibre grating laser has been fabricated using the grating. The laser threshold is 20 mW. When pumped with 90 mW light at 980 nm, the laser gives an output of 1.1 mW. Its signal-to-noise ratio is better than 60 dB. It is demonstrated that the laser is single mode operation by means of a Fabry-Perot scanning interferometer.

Influence of the second cladding on the properties of four-layer large flattened mode fibers

A theoretical method to analyze four-layer large flattened mode (LFM) fibers is presented. The influence of the second cladding on the properties of four-layer LFM fiber, including the fundamental and higher-order modal fields, effective area, bending loss, and dispersion, are studied by comparison. At the same time, the reasons for the different characteristics are considered. The obtained results indicate that the effective area of the four-layer LFM fiber is about 1.6 times larger than that of the conventional standard step-index fiber and the fibers have better bend-induced filtering ability than three-layer LFM fibers. (C) 2007 Society of Photo-Optical Instrumentation Engineers.

Design guidelines and characteristics for a kind of four-layer large flattened mode fibers

A theoretical method to analyze a kind of four-layer large flattened mode (LFM) fibers is presented. The properties of the fiber, including the fundamental and higher-order modal fields, effective area and bending loss are discussed by comparison. At the same time, the reasons for the different characteristics are considered. The obtained results indicate that the effective area of the four-layer LFM fiber is about 1.3 times larger than that of the conventional standard step-index fiber and the fiber can suppress the higher-order modes via bending effectively. The four-layer LFM fiber has less efficient bend-induced filtering ability than the conventional step-index fiber; however, it has more efficient filtering ability than the three-layer LFM fiber. (C) 2007 Elsevier GmbH. All rights reserved.

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.

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.