Injection characterization of packaged bi-directional diamond shaped ring lasers at 1550 nm

Abstract

The Air Force Research Laboratory, Binoptics Corp., and Infotonics Technology Center worked collaboratively to package and characterize recently developed diode based ring lasers that operate at 1550 nm in a diamond shaped cavity. The laser modes propagate bi-directionally; however, uniaxial propagation may be induced by optical injection or by integrating a mirror. Round trip cavity length was 500 μm in 3.5 μm wide ridge waveguides, and four polarizationmaintaining lensed fibers provided access to the input and output modes. A signal from a tunable diode laser, incident at one port, served to injection lock both of the counter-propagating circulating modes. When the input signal was timeencoded by an optical modulator, the encoding was transferred to both modes with an inverted time-intensity profile. Performance, in terms of fidelity and extinction ratio, is characterized for selected pulsed and monochromatic formats from low frequencies to those exceeding 12 GHz. A rate equation model is proposed to account for certain aspects of the observed behavior and analog and digital applications are discussed.