International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper presents the results of installing a distributed feedback (DFB) laser transmitter and the appropriate optical receiver in an operational site. Frequencies from 1435 to 2400 megahertz are transported intact from a remote site to a local site. From the theoretical calculations, 10 dB of dynamic range may need to be recovered by the use of an automatic gain circuit. The actual device is a delight, needing no additional circuitry to meet specifications. Predictions of performance were made from calculations. The installed system was measured for 1 dB compression point and for figure of merit.

The duty-cycle randomness (DCR) lying the Bragg grating of the distributed feedback (DFB) lasers introduced by the fabrication process is inevitable even with the state-of-the-art technologies such as the electron beam lithography and dry or wet etching. This thesis investigates the impact of grating DCR on DFB laser performance through numerical simulations. The result reveals that such a randomness causes a reduction on the side mode suppression ratio (SMSR), and deteriorates the noise characteristics, i.e., broadens the linewidth and increases the relative intensity noise (RIN). With the grating DCR, the effective grating coupling coefficient decreases as evidenced by the reduced Bragg stopband width. However, the longitudinal spatial hole burning (LSHB) effect in the DFB lasers can somewhat be diminished by the grating DCR. The seriousness of these effects depends on different grating structures and their coupling strengths. Our simulation shows that a degradation of 17dB can be brought to the SMSR of the uniform grating DFB lasers with their duty-cycles taking a deviation of ±25% in a uniformly distributed random fashion. It also broadens the linewidth of the quarter-wavelength phase-shifted DFB lasers by more than 2.5 folds. The impact of this effect on the RIN is moderate – less than 2%. All the performance deteriorations can partially be attributed to the effective reduction of the grating coupling coefficient around 20% by such a DCR. / Thesis / Master of Applied Science (MASc)