SBIR-STTR Award

Aculight proposes the development of a blue/green laser system for underwater communications. The laser comprises a hybrid system in which a directly modulated 1064nm semiconductor laser is amplified in a multistage Yb-doped fiber amplifier and subsequently frequency doubled in non-critically phase match LBO crystal. In the phase I program all key specifications will be demonstrated in a laboratory breadboard. We will demonstrate >10W output power at or around 532nm with pulse durations in the range 0.5-5.0ns and pulse repetition frequencies (PRF) in the range 100kHz-10MHz. The proposed architecture, which overcomes the PRF, size, weight and efficiency limitations of current laser technologies, is ideally suited to the requirements of the solicitation and to the targeted deployment environment. In a phase I option we will operate our seed laser in a single frequency regime as required by the primary application. The option experiments will enable us to bridge the phase I demonstration to a phase II deliverable with minimal difficulty. The Yb fiber amplifier at the heart of the system is based around an established pulsed fiber laser product platform which will form the basis of the packaged laser delivered by Aculight in the event of a phase II award.

Benefits:
High power lasers have many potential applications in DOD systems. The proposed application for underwater communication represents a significant opportunity for Aculight. With the rapid increase in UAVs and UUVs, and the corresponding requirements for compact, efficient and lightweight laser sources, we see the potential for an important and sizeable market. In addition to communications, Navy missions such as mine detection and other optical technologies that utilize blue-green lasers could also benefit from the development of the laser system. Aculight's business philosophy is to target dual-use technologies that have both military and volume commercial applications. The proposed high power green laser combining high power and high brightness with low signal noise at high repetition rates has a great potential to replace existing mode-locked DPSS lasers and directly modulated LDs for medical, material processing and defense applications, such as micromachining, marking, and semiconductor processing

In response to the SPAWAR solicitation for a blue/green laser for underwater communications Aculight propose the development of a hybrid laser system comprising a low-power semiconductor seed source generating the desired pulse duration and repetition frequency, followed by a multistage Yb-doped fiber amplifier to generate the peak and average power required for efficient harmonic conversion. The achievable peak powers and near perfect beam quality allows high conversion efficiency with either KTP or non-critically phase matched LBO, one of the most rugged and robust harmonic conversion materials. Our proposed fiber laser solution will deliver > 10 W of average 532nm power at 100kHz-10MHz rep-rates in a small (~ 0.1 ft3), air or conduction-cooled package. Aculight will develop electronics control circuitry capable of varying the pulse format to address the variable data rate requirements. State of the art optical fibers and specifically engineered fiber components will be integrated into a high gain amplifier in which nonlinearities are mitigated at a level consistent with the specification. A frequency doubling module incorporating a collimator and nonlinear crystal will be integrated with the laser system. In an option task Aculight propose an upgrade to the system to address higher energy or higher data rate requirements.

Keywords:
Undersea-Communications, Undersea-Communications, Frequency Conversion, Fiber Lasers