SBIR-STTR Award

High energy lasers (HELs) are in great demand for industrial material processing and directed energy weapon systems for defense and security. Compared to other laser platforms, fiber lasers have shown their excellence in producing high beam quality and high brightness HELs by taking advantages of their inherent attractive aspects including optical confinement in glass fibers, compactness, robust operation, easy thermal management, high power scalability, alignment-free operation, and low maintenance. Most kW-class HELs in development today are based on Yb3+-doped silica glass fiber lasers operating around 1 m wavelength because of their high optical efficiency. But 1 m lasers are neither eye-safe nor highly transparent in the atmosphere, which have severely restrained their in-field applications. 2 m lasers are preferred over 1 mm and 1.5 m lasers for long-range applications including direct energy laser weapon, LIDAR (LIght Detection And Ranging) and sensing systems, and direct optical communication because atmospheric scattering, atmospheric distortion, and thermal blooming are significantly reduced by operating at longer wavelengths. NP Photonics is a pioneer in the design and fabrication of highly doped optical fibers and the development of high-performance fiber lasers at 2-micron. We propose to develop a scalable high-efficiency high-atmospheric-transparency HEL source based on spectrally combined Ho-doped germanate fiber lasers at 2.1-micron that are in-band pumped by Tm-doped fiber lasers at 1950 nm.

Benefit:
High power fiber laser and amplifier systems are finding application and acceptance in wide variety of industrial and military applications where the high integration, high efficiency, and high reliability (no free space surfaces, and no alignment) are important. Fiber laser systems have the advantage of an all-fiber design that offers power scalability and environmental robustness. There are applications in cutting/welding, optical communication and use in space or airborne platforms. One of the most important characteristics of this wavelength is that it will be less affected by the atmospheric operation near marine wave boundary layer (MWBL) and its eye-safe operation from scattered light. kW class fiber lasers operating in the 2-micron band have immediate military benefits for directed energy demonstrations, including counter-improvised explosive devices (IED), counter-rockets, artillery, mortars, counter-measures etc.

Keywords:
Optical Efficiency, Optical Efficiency, Optical amplifier, High Energy Laser, Electro Magnetic Spectrum, spectral beam combining, Marine Wave Boundary Layer

High energy lasers at 2 microns are in great demand for industrial material processing and directed energy weapon systems for defense and security. NP Photonics is a pioneer in the design and fabrication of highly doped optical fibers and the development of high-performance fiber lasers at 2 microns. In this program, we propose to develop a scalable high-efficiency high-energy Ho-doped germanate fiber laser at 2 microns in-band pumped by Tm-doped fiber lasers at 1950 nm. During the Phase I program, we successfully demonstrated the feasibility of fabricating high-efficiency kW-class fiber lasers at 2 microns. In Phase II we will focus on fabricating large-mode-area Tm-doped and Ho-doped germanate fibers and developing high-energy fiber lasers at 2 microns with improved efficiencies. In Phase II Options I and II, we will focus on developing in-band pumped high-efficiency 2-micron kW-class fiber lasers meeting or exceeding the requirements of the Navys applications.

Benefit:
The successful completion of the proposed program can bring immediate military benefits. It can be integrated into DODs kW level 2-micron fiber laser systems and used in infrared missile countermeasures, high resolution, long-range target identification, direct-energy weapons, and remote sensing of biological or chemical agents. Successful completion of this project will directly support the Navy, particularly as we have shown that wavelength multiplexing readily enables power scaling to 100kW class and beyond. The laser system can be deployed ultimately in a submarine or other Navy platform to advance the future Navy warfighting capability. Both the power specifications and wavelength of operation and electrical to optical efficiency could be tested at a NSWC Dahlgren, high-energy laser test facility. In addition, there exist many transition opportunities in DoD for high-power lasers; we will identify DoD laboratories with interest in high-power fiber lasers for collaboration and testing of our fabricated devices, such as AFRL, NRL, NUWC, and ARL, to name a few. We have connections and existing relationships with prime companies who will also benefit from using high-power fiber lasers, amplifiers, or optical sub-assemblies. It can also be used for industrial manufacturing, material processing, free-space communications, and specialty fiber lasers.

Keywords:
in-band pumping, high-energy lasers, Fiber lasers, germanate fibers, 2-micron laser, Tm laser, Ho laser, amplifiers