Investigation of spectral and intensity noise properties of long wavelength triangular ring lasers

This thesis describes the study of long wavelength triangular ring lasers operating at close to 1.3mum in the InGaAsP/InP material system. The combination of high spectral purity and cleave-free operation has made these devices potentially useful as monolithically integrated light sources in OEIC chips, for optical data link applications.;The triangular ring laser was fabricated in a ridge waveguide structure for single lateral mode operation. A high temperature, low pressure Chemically Assisted Ion Beam Etching (CAIBE) recipe was developed to produce dry etched laser ridges and facets in indium-containing material. Indium chloride redeposition was minimized by operating the CAME in the chlorine supply limited regime. Very smooth and vertical laser facets were produced, with the surface roughness less than 400A. PECVD-deposited amorphous carbon was developed as a CAME etch mask, with good selectivity, etch stability and ease of removal.;The ring laser was shown to hop between compound cavity modes as the temperature was varied. The compound cavity effect was due to residual backscattering from the ring laser turning mirrors. Effective laser gain profile analysis indicated that triangular ring laser spectral properties were primarily determined by the compound cavity effect, with spectral hole burning playing a significant but secondary role in this material.;Ring laser Relative Intensity Noise (RIN) properties were characterized in detail, and compared with DFB, FP and turning mirror V lasers. Triangular ring lasers exhibited significant low frequency RIN enhancement, probably caused by a partition noise effect between the two output beams. A bidirectional ring laser mode model was proposed, with the beam ratio of each mode determined by the backscattering strength. The estimated backscattering reflectivity was 10-4 to 10-3. The unusual ring laser RIN results were quantitatively explained using this model.;Laser linewidth of these devices, as measured using a scanning interferometer, appeared significantly broadened, due to residual feedback from the measurement setup. External cavity modes and coherence collapse at various levels of optical feedback were also observed directly.