Accession Number : ADA188454

Title :   Fiber-Coupled External-Cavity Semiconductor High Power Laser.

Descriptive Note : Rept. for Jan-Dec 86,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS

Personal Author(s) : Rediker, Robert H ; Anderson, Kristin K ; Liew, So K ; Corcoran, Christopher J

PDF Url : ADA188454

Report Date : Jan 1987

Pagination or Media Count : 6

Abstract : Last year's annual report described the high spectral purity of the output from an ensemble of five discrete diode lasers when operated cw. The linewidth of the cw output of this external-cavity-controlled ensemble of diode lasers was shown to be less than 7.5 MHz (approx 2 x 10 to the -8th power of the center frequency). Also reported last year was high-spectral-purity pulsed output from this external cavity controlled laser. In 1986 the pulsed operation of this laser was investigated in detail both experimentally and theoretically. Linewidths of the order of the 7.5-MHz instrument resolution have been obtained. To achieve this high spectral purity in a pulse mode of operation, three alternate gain elements are operated cw and the intermediate two elements are pulsed. For a coherent ensemble of only three alternate gain elements, the spacing between the major intensity maxima in the Fourier plane (the filter plane) is decreased by a factor of 2 relative to the spacing with all five elements operating coherently. As a results, the lasing threshold of the three-element ensemble is much higher because significant radiation hits the opaque areas of the filter. A calculation of the single-pass filter transmission of this case yields a value of 0.48 as compared to the transmission of 0.92 when all five elements are running.

Descriptors :   *FILTERS, *LASER CAVITIES, *SEMICONDUCTOR LASERS, COHERENCE, CONTROL, EXTERNAL, FOURIER ANALYSIS, FREQUENCY, GAIN, HIGH RATE, LASERS, OPACITY, OPERATION, PULSES, PURITY, SPECTRA, YIELD

Subject Categories : Lasers and Masers
      Solid State Physics
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE