Watt-class semiconductor optical amplifiers (SOAs) at 1550nm are an attractive alternative to replace erbium-doped fiber amplifiers (EDFAs) in various applications including free space optical communications (FSO), with the potential to be more efficient, compact, and cost-effective while providing high-power diffraction-limited output. We present a single mode fiber-coupled packaged SOA delivering >30dBm (1.2W) of continuous wave ex-fiber power at 1550nm with 16dB of overall gain, enabled by recent advancements in diffraction-limited output from tapered semiconductor amplifiers. Preliminary data communications measurements are presented, with an open eye diagram achieved with >1W of output power at 10Gbps using the differential phase shift keying (DPSK) communications format. Watt-class collimated and fiber-coupled SOAs are available and being shipped to customers now.

Coherent Beam Combination (CBC) is used for Laser Directed Energy Weapons (LDEW) because of its power scalability and ability to produce high quality, low-divergence output beams capable of high-speed compensation for atmospheric turbulence. Traditional CBC optical arrays, comprised of many individual optics, suffer from mechanical and thermal stability issues as power levels and size increase. PowerPhotonic monolithic lens arrays offer a robust, scalable solution that simplifies system alignment and offers the mechanical and thermal stability required to succeed at current and future LDEW power levels. Unique manufacturing techniques allow PowerPhotonic to continue to increase the form factor of these monolithic arrays to keep up with power scaling requirements. Newly implemented tools have demonstrated a 4x increase in clear aperture capability with room for further improvement with more mechanical modifications to the manufacturing system. Large monolithic lens arrays have the power handling and dense packing capabilities to support LDEW systems aiming to achieve megawatts of coherently combined power and beyond.

Power scaling of fiber lasers and amplifiers is currently limited by nonlinear optical effects, such as transverse mode instability (TMI) and stimulated Brillouin scattering (SBS). Addressing optical nonlinearities through a material approach allows for such challenges to be confronted at their source - the interaction of the light and the material without the need for complex fiber designs. However, effectively mitigating these issues through materials engineering will require much higher dopant concentrations than are now typical for the chemical-vapor-deposition (CVD)-derived silicate glasses from which modern commercial laser fibers are made. As dopant concentrations are increased, new fabrication challenges arise, such as draw-induced, refractive-index changes not related to frozen-in stresses. This paper presents an initial report of these new challenges and offers suggestions to their cause.

Self Q-switched Nd, Cr:YAG laser rods were produced via additive manufacturing of transparent ceramics and lased. Two identical rods were produced and air annealed at different temperatures to vary the Cr⁴⁺ concentration. The pulse width varied based on the Cr⁴⁺ concentration from 10 to 18ns. The pulse repetition rate increased with the pumping intensity, up to 4 pulses within a 200μs pumping time. The pulse energy remained nearly constant at about 8mJ, with some variation attributed to thermal lensing.

Fiber laser technology has gained prominence as a key area in optical research, characterized by rapid progression and notable advancements. This paper delves into the advancements of fiber laser technology, aiming to shed light on its evolution, significant contributors, and current trends. Our analysis, drawing on data from leading scientific databases covering the period from 1995 to 2023, reveals a marked increase in research activities, underscoring the growing importance of fiber lasers in sectors like industrial machining and medical therapies. We identify and classify the primary research areas, highlighting leading research institutions and countries spearheading this field. The study also explores collaboration networks to illustrate the interconnectedness of global research efforts. We focus on significant technological breakthroughs in fiber laser development, including their increasing compactness, energy efficiency, and versatility, reflecting the industry's response to market demands. This paper aims to provide a detailed overview of fiber laser literature, guiding future research, fostering collaborations, and laying a foundational knowledge base for newcomers to the field. Our findings underscore the need for continued investment in fiber laser research, recognizing its potential to drive forward laser technology and impact various scientific and industrial domains.