Double optical feedback system for a single-mode vertical-cavity surface-emitting laser

摘要

Abstract. Ongoing tests involving the application of double optical feed-nback to a vertical-cavity surface-emitting laser u0001VCSELu0002 are resulting inndemonstrable and significant improvements in oscillation linewidth andnfrequency stability. We look into the workings of a double optical feed-nback system for a Fabry-Pérot-type diode laser. We describe a single-nmode VCSEL that is characterized by a narrow oscillation linewidth andna stable output intensity that shows no trace of the low-frequency fluc-ntuation u0001LFFu0002 that so often occurs in single optical feedback diode lasers.nInitial tests use a beat note to do this. From there, we calculate thensquare root of the Allan variance to determine the level of frequencynstability. We also evaluate the degree of LFF suppression achieved us-ning its spectrum density and compare those results with what we ob-ntained through single and double optical feedback and with no feedbacknwhatsoever. © 2010 Society of Photo-Optical Instrumentation Engineers.nu0003DOI: 10.1117/1.3284784