Generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet radiation at 271.2 nm.

This paper presents to our knowledge a first time study on the generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet (UV) radiation at 271.2 nm. The work is based on frequency summing of coherent green (G: 510.6 nm) and yellow (Y: 578.2 nm) radiations of a copper-HBr laser in a ß-barium borate crystal. Average and peak sum frequency conversion efficiencies of about 13% and 16%, respectively, are obtained. The sum frequency results are experimentally analyzed in terms of the extent of matching of green and yellow pump radiations in space, time, and frequency domains. The result is of high significance for many applications in photonics components fabrication, semiconductor technology, and spectroscopy.

Studies on the spectral purity of copper-hydrogen bromide laser radiations.

This paper presents, for the first time to the best of our knowledge, the linewidth, frequency, and stability characteristics of a copper-HBr laser. These spectral purity attributes were found to be critically linked with the electrical input power and HBr concentration, unlike that of the optical resonator. Variation in green and yellow radiation linewidths from 4 to 4.5 GHz and from 6.5 to 8.8 GHz, linewidth fluctuations from 50 to 150 MHz and from 60 to 530 MHz as well as frequency fluctuations from 10 to 100 MHz and from 410 to 10 MHz were observed when varying the input power and HBr concentration. These results are comprehensively analyzed in terms of isotopic shift, hyperfine splitting, line broadening, and temperature and gain distribution effects relevant to this laser.

Study on the quality of interference fringes from a pulsed UV source for application in a biprism based fiber Bragg grating writing.

This paper presents a study on the quality of interference fringes formed from a pulsed UV (255 nm, 5.6 kHz, and 40 ns) source for an application in writing fiber Bragg gratings (FBGs). The interference fringes of separation of about 8 microm, formed by a biprism of apex angle 2 degrees , were studied for their contrast, evolution of contrast, and positional and intensity stability over a period of 5 min (over 10(6) pulses). Second harmonic UV (255 nm) sources of different spatial coherence and pointing stability characteristics were employed as the inputs. It is established that the UV fringes contrast and interference pattern stability with time is largely controlled by the optical resonator geometry of the fundamental wavelength (510 nm) copper vapor laser (CVL) oscillator. In particular, the generalized diffraction filtered resonator (GDFR) CVL produced the highest quality second harmonic beam with the highest fringes contrast and stability. The implications of these results were studied by employing these UV sources for the fabrication of the C-band FBGs by a 24 degrees apex angle biprism.