Beam-Combined Pulsed Fiber Lasers

Project Overview

Pulsed lasers are widely used in a variety of applications. For many national security applications, the desired laser pulse characteristics include kW-class average power, 10 kHz repetition rate, nanosecond pulsewidth and diffraction-limited beam quality. Fiber lasers can satisfy most of these characteristics and, with beam combining, the pulse energy requirement as well. We investigated the Raman combining technique. Raman combining is unique because it can take advantage of the recent maturation of XLMA fiber amplifiers. These XLMA fiber amplifiers have significantly higher extractable pulse energy over conventional fiber amplifiers but suffer poor beam quality. We showed that a Raman combiner can power-combine XLMA fiber amplifiers while maintaining diffraction-limited beam quality. Both crystal and fiber beam combiners have been investigated via experiments and modeling. We have validated their power handling and approaches to improve their conversion efficiency.

Mission Impact

This laser research develops science and technology tools and capabilities to meet future national security challenges. More specifically, it improves the security and resilience of the nation and its critical infrastructure from drone attacks and explores solutions to emerging security challenges associated with technology surprise in space and other relevant domains. Other impacts include DOE's energy security mission and related environmental challenges.

Publications, Presentations, and Patents

Yu, C. X., V. Khitrov, P. Pax, C. Mart, M. Runkel, M. Messerly, J. Dawson, J. Zhang, and M. Dubinskii. "First demonstration of dispersion-shifted LMA silica fiber in a high-power 1.6-mm laser." Proc. of SPIE 11981, Fiber Lasers XIX: Technology and Systems, (2022): 119810S.

C. X. Yu, J. Dawson, M. Messerly, and G. Allen, "Raman Fiber Technology for DEW Illuminator Application" (Presentation, DEPS 2022 Spring S&T Conference, Mobile, AL, 2022).

C. X. Yu, V. Khitrov, G. Allen, P. Pax, M. Messerly and J. Dawson. 2022. "Raman Combining of Fiber Lasers in the 1.55-mm Regime" (Presentation, Paper AW4A.5, Laser Congress 2022, Advanced Solid State Lasers Conference, Tacoma, WA, 2022).

C. X. Yu, P. Pax, M. Cook, V. Khitrov, S. Wu, W. Moore, M. Runkel, M. Messerly, J. Dawson and M. Dubinskii, "Distributed Bandpass Filtering in a 40-mm core LMA fiber" (Presentation, Paper JW6A.1, Laser Congress 2022, Advanced Solid State Lasers Conference, Tacoma, WA, 2022). 

A. Yandow and C. X. Yu. 2023, "Raman Gain Measurements at the Boson Peak in Phosphosilicate Fiber" (Presentation, Paper JM4A.1, Laser Congress 2023, Advanced Solid State Lasers Conference, Tacoma, WA, 2023).