ABSTRACT
Phase-modulated (PM) spectral failsafe systems are necessary to promptly terminate amplification processes following accidental seeding of a high-power laser chain with a non-PM pulse to prevent optical damage. In this work, we present a reliable spectral failsafe system that can indicate the presence or absence of sufficient PM light. This requirement is met by combining dual temperature-sensitive fiber Bragg gratings detection with high-speed RF amplitude comparisons. The failsafe trigger signal is generated when the spectral power at the peak sideband exceeds that at the center. The spectral failsafe system has the ability to distinguish between adequate and inadequate PM pulses, and it exhibits significant robustness in pulse width, TEC temperature drift, and DFB wavelength drift in experiments, making it valuable for safe high-power laser operations and providing a useful reference for other detection system designs.
ABSTRACT
A fiber laser injection system used as a seeder for a high-power laser facility of inertial confinement fusion was designed to meet stringent requirements. Herein, we demonstrate the fiber laser injection system, whose output single-pulse energy reaches the millijoule class. With two-stage amplitude modulators, the system produces a pulse with a higher pulse shaping capability. In addition, amplifying the pulse with large-mode-area fiber and single polarization, large-mode-area photonic crystal fiber (PCF) ensures a good beam quality output. In this proof-of-principle experiment, the long-term stability of FM-to-AM modulation and pulse energy is demonstrated. The successful demonstration of this laser injection system holds great significance for future high-power laser drivers.
