COHERENT COUPLING OF MULTIPLE LASER DIODE ARRAYS BY INJECTION LOCKING

PHYSICAL OPTICS CORPORATION (POC) PROPOSES A COMPACT, LIGHT-WEIGHT, HIGH-EFFICIENCY AND HIGH-POWER COHERENT OPTICAL SOURCE SYSTEM. THIS SYSTEM WILL CONSIST OF MULTIPLE SLAVE DIODE LASERS (OR ARRAYS) FREQUENCY-LOCKED TO A WELL-CONTROLLED MASTER DIODE LASER WHICH WILL OPERATE AT A SINGLE LONGITUDINAL MODE WITH A NARROW LINEWIDTH. FREQUENCY LOCKING BETWEEN THE MASTER AND SLAVES CAN BE OBTAINED BY TUNING THEIR TEMPERATURES AND BIAS CURRENTS IN SUCH A WAY THAT THEIR FREE-RUNNING FREQUENCY SEPARATION IS WITHIN THE LOCKING BANDWIDTH. POC PLANS TO USE THE MULTIGRATING HOLOGRAM FAN-OUT EFFECT FOR A SIMULTANEOUS LOCKING OF SEVERAL SLAVE DIODE LASERS (OR ARRAYS) TO A SINGLE MASTER LASER. THE OPTICAL OUTPUTS OF THE LOCKED SLAVES EMITTING A SINGLE-LOBE FAR-FIELD AT MASTER LASER FREQUENCY ARE COHERENTLY COMBINED THROUGH THE FAN-IN FUNCTION OF THE MULTIGRATING HOLOGRAM, WHICH ALSO SERVES AS A SPECTRAL AND SPATIAL FILTER BY BRAGG LAW. INCREASING THE SLAVE LASER NUMBERS WILL BOOST THE AVAILABLE COHERENT POWERS OF THIS SYTEM. IT IS POSSIBLE TO FURTHER ENHANCE COHERENT OUTPUT POWER BY LOCKING SEVERAL SYSTEMS TOGETHER. AN OEIC DESIGN OF THIS SYSTEM IS EXPECTED WHICH WILL HAVE A SURFACE EMITTING FEATURE ACHEIVED THROUGH INCORPORATING GRATINGS OR MICROLENSES. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THE PROPOSED TECHNIQUE CAN PROVIDE A HIGH-POWER COHERENT OUTPUT WITH A DIFFRACTION-LIMITED SINGLE-LOBE FAR FIELD AT A SINGLE AND NARROW SPECTRAL LINE. THIS COMPACT AND HIGH-EFFICIENCY COHERENT OPTICAL SOURCE HAS POTENTIAL FOR FREE-SPACE COMMUNICATION, OPTICAL PUMPING, NONLINEAR OPTICS, PARALLEL OPTICAL SIGNAL PROCESSING, OPTICAL COMPUTING AND NUMEROUS TACTICAL APPLICATIONS. KEY WORDS - COHERENT COUPLING, DIODE LASER, INJECTION LOCKING, MULTIGRATING HOLOGRAM