100 kHz Narrow-Linewidth Burst-Mode MOPA Laser System With Uniform Envelope

Abstract

In this study, a 100-kHz narrow-linewidth burst-mode laser system combined with a master oscillator power amplifier (MOPA) structure was reported with a stable pulse burst profile over 2 ms duration. A theoretical model was established to characterize and compensate the variation characteristics of coefficient of variation (COV) within a burst envelope for the double-pass three-stage amplification system, in terms of different parameter factors. Simulated results yielded similar tendency with the measured ones. For a stable burst envelope with a COV of 2.72% and 2.93%, output pulse energy at a 100 kHz repetition rate was scaled up to 1.08 and 4.38 mJ in the case of an input average pulse energy of 8.6 and 116.51 nJ, respectively. Corresponding Mx2 and My2 values with 2.2 and 2.4 were endowed with 1.08 mJ output single-pulse energy and 2.7 and 2.1 for 4.38 mJ pulse energy. The spectral linewidth of amplified pulses was measured to be less than 83.1 and 67.9 MHz, with respect to output pulse duration of 10.3 and 96.1 ns, respectively.

Pre-Shaped Burst-Mode Hybrid MOPA Laser System at 10 kHz Pulse Frequency

“…Figure 2 exhibits the experimental schematic of a fiber-bulk pulse burst laser system, with two primary segments of both an all-fiber system and a free-space operation. The continuous wave (CW) fiber laser source, over a 1.17 cm −1 span of the tunable emission spectrum (1064.109–1064.241 nm), was seeded into an integrated Yb-doped fiber amplifier (YDFA) module with two amplifier stages to scale the laser’s power; the relevant optical configuration of the YDFA is illustrated in [ 31 ]. An acousto–optic modulator (AOM), with a high contrast ratio, connects the two fiber ports into the optical path, establishing a train of the burst envelope characterized by the desired intensity distribution.…”

“…Typically, a distribution trend is found with the obvious deficiency of a lower gain fluence in the front end of the amplified envelope with respect to excessive amplification at a higher gain factor. For such inhomogeneous envelopes, a theoretical model has been created in our previous research to guide its compensation based on the amplification delay method, realizing a uniform burst profile with a 2 ms duration for a flat-top input [ 31 ]. This method could be appropriately applied in burst-mode systems with lower duty cycles, input energies, pump powers, and thermal deposition because of the easier establishment of dynamic equilibrium during pumping and amplification.…”