By using a polarization controller, a semiconductor laser apparatus oscillating in the transverse magnetic mode in mode-locked state is realized, and a short optical pulse is generated. By coupling this mode-locked semiconductor laser to a wavelength conversion element, a second harmonic wave is generated, and an even shorter optical pulse is obtained at a higher power.

A guided-mode resonance filer is provided which can be used as an optical filter with very narrow line width and as an efficient optical switch. Diffraction efficiencies and passband frequencies are calculated based on guided-mode resonance properties of periodic dielectric structures in a waveguide geometry. The guided-mode resonance filter preferably includes means for changing various parameters within the grating so as to change passband frequencies in response thereto. Also, the present invention envisions a narrowband tuneable laser having a diffraction grating of the present invention placed within a laser cavity to provide narrowband optical wave output from the narrowband tuneable laser In another preferred embodiment, the present diffraction grating can be supported by a semiconductor substrate, preferably adjacent to a semiconductor laser for fine-tuning the output of the semiconductor laser. In still another preferred embodiment, the present diffraction grating can be placed between thin-film layers to enhance thin-film performance characteristics.

A laser chamber has angled reflectors that reflect acoustic and shock waves away from the laser discharge area to minimize acoustic and shock wave disturbances. The angled reflector may have different configurations to assist in the dissipation of the acoustic and shock waves. For example, the angled reflector may have a modulated reflective surface, such as having grooves or holes defined within the surface. Further, the angled reflector may have a reflective surface with acoustic and shock wave absorbing properties. The reflective surface with absorbent properties may be a felt metal or have multiple layered porous surfaces. In addition, the walls of the laser chamber may be modulated to assist in the dissipation of the acoustic waves and shock waves through absorption, scattering, and by generating interference within the reflected waves. Multiple layered porous surfaces may be used along the walls to absorb and scatter incident waves. The walls of the laser chamber may also be covered with an acoustic and shock wave absorbing material, such as felt metal. In other embodiments, the walls of the laser chamber are modulated with grooves, such as triangular or rectangular horizontal grooves, which scatter incident waves and generate interference within reflected waves.

A fiber optic device basically comprising an optical fiber/interference filter combination finds useful application in optical communication systems for wavelength selection or bandwidth selection from a multiwavelength light source or emitter. If the emitter is a semiconductor laser, the device may be also employed to provide single longitudinal mode control at the selected wavelength or bandpass.

The present invention contemplates an integrated oscillator-amplifier system for deep UV generation. The system employs a long cavity oscillator to lengthen the pulse build-up time and to control the pulse spectral bandwidth. Meanwhile the system employs a short cavity amplifier to shorten the energy extraction time to produce a single short pulse with good energy extraction efficiency. The system further integrates the oscillator and the amplifier by inserting the amplifier cavity inside the oscillator cavity via a mirror of low reflectivity. As a result, the integrated system has a long build-up time to generate a seed pulse in the long cavity oscillator and has a short energy extraction time to generate a short amplified single pulse in the short cavity. Consequently, the integrated system can accommodate a relatively long pump pulse to produce a single short amplified pulse suitable for deep UV laser generation.