LASER SWEPT SOURCE WITH CONTROLLED MODE LOCKING FOR OCT MEDICAL IMAGING

摘要

An optical coherence analysis system uses a laser swept source that is constrained to operate in a mode locked condition. This is accomplished by synchronously changing the laser cavity's gain and/or phase based on the round trip travel time of light in the cavity. Many high-speed wavelength swept laser sources emit pulses synchronized with the round trip time of the cavity as part of a nonlinear optical frequency red shifting process. Stable pulsation is associated with smooth tuning and low relative intensity noise. Addition of mode- locking methods to this class of lasers can control and stabilize these lasers to a low clock jitter and RIN state, and in specific cases allow long - to - short wavelength tuning in addition to the usual short - to - long (red shifting). The laser may comprise a SOA (410), a tunable Fabry- Perot - Filter (412) as one reflector and an Output coupler (405) in an optical fiber (406) to adjust the cavity lenght.