Low Power Consumption Laser for Undersea Communications

"The Navy is faced with the problem of transmitting data betweenvarious platforms and underwater instrumentation. Security andsafety prevent physical contact between the platform and the datasource so remote optical communication is necessary. A frequencydoubled Nd:YAG laser is used in these situations because itproduces a green beam for efficient transmission through coastalwaters. Unfortunately, these lasers are inefficient so they arerelatively large and power hungry. Aculight offers uniquesemiconductor laser technology that requires only 5% of theelectrical power of comparable Nd:YAG lasers and can be directlymodulated and fiber coupled. The innovation enables the use ofblue/green lasers in battery-powered instruments that mustoperate underwater for extended periods. We demonstratedelectrical efficiencies of 30% in the Phase I program. Thistechnology can yield lasers with optical powers ranging from 100mW to over 100 Watts and wavelengths from ultraviolet to mid-infrared. In this program, we propose to build a compact laserthat will produce a high quality red beam that can be upgraded togreen when the diodes become available. The red laser, althoughmerely a first step, has a detection distance that is only 20%shorter than a comparable DPSS laser.BENEFITS: The high brightness visible semiconductor laser we will develop has direct application as an illuminator for photodynamic therapy drugs. In some cases, the laser energy