Abstract
A bidirectional 793 nm diode-pumped actively Q-switched Tm3+, Ho3+-codoped silica polarization-maintaining (PM) double-clad (DC) fiber laser is reported. With this fiber laser, 55 W of average output power with 100 ns pulse width at 200 kHz repetition rate and 2.09 µm wavelength is obtained. The pump power injection with end-caps fusion-spliced on fiber tips provides good power stability (< 1.1%) and beam quality factors (M2 < 1.7). The fiber laser output beam polarization factor is 97.5%. At 55 W, no thermal-induced damage is observed on any optical element, and power scaling of the laser is only pump-power-limited in the range of the total available pump power (180 W).
Highlights
Pulsed fiber lasers emitting at wavelengths around 2 μm are promising sources of laser radiation for eye-safe lidar systems, range finders or countermeasures by nonlinear optical generation of mid-infrared radiation via optical parametric oscillation (OPO)
The end-caps fusion-spliced on both fiber tips lead to a decrease of the end-face pump power density that was responsible for the fiber end-face damaging in previous experiments [14,15,16]
No thermal-induced damaging is observed on the fiber or any bulk optics when pump power is increased, and the power scaling of the laser is only pump-power-limited in the range of the total available pump power of our setup
Summary
Pulsed fiber lasers emitting at wavelengths around 2 μm are promising sources of laser radiation for eye-safe lidar systems, range finders or countermeasures by nonlinear optical generation of mid-infrared radiation via optical parametric oscillation (OPO). In MOPA systems, a low power modulated seed emitting around 2 μm is power-amplified with several amplification stages to get the desired output power. Nanosecond pulse generation at 2 μm with all-fibered MOPA systems, delivering high average output power up to 100 W, have been successfully demonstrated in several studies [1,2,3]. Fiber MOPA sources suffer from higher volume due to the number of isolated amplification stages needed to get a stable high power delivery laser source. In some cases where a Distributed Feedback (DFB) laser diode is used as a seed laser, MOPA systems may suffer from higher sensitivity to fiber nonlinearities compared to single oscillator fiber laser sources [4]. The picometer range linewidth of DFB laser diodes decreases the power threshold of the Brillouin scattering nonlinear effect
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