Compact lasers, emitting sub-ns, high energy and peak power pulses in wavelength near 1.3 µm spectral range are essential for wide variety of applications such as autonomous vehicle, remote sensing, frequency conversion and so on. Some of the recent and promising applications require both high pulse energy (~mJ) and peak power (~1 MW) at frequencies above 100 Hz. The diode-pumped short-cavity oscillators, working in passively Q-switching regime of operation, are now established as ultra-compact laser sources, capable to produce optical pulses with energy 1-1000 µJ and sub-ns duration with high beam quality [1,2]. This is well developed mostly for Nd +3 doped active media emitting mainly at 1 µm transition F 3/2 → 4 I 11/2 . In addition, to achieve single transfer mode of operation at high excitation energy a fiber coupled diode with more than 100 W peak power was used for longitudinal pumping. However the transition 4 F 3/2 → 4 I 13/2 around 1.3 μm has substantially smaller emission cross which affects the formation of the leading edge of the Q-switched laser pulse and hence the obtaining of shorter pulse duration  and much higher pump energy is required. At present, diode laser bars with high fill factor can emit 200-300 W at pump wavelength in QCW operational mode, but the beam profile of a single diode laser bar is highly asymmetric to be used directly as a TEM 00 -pump source.In this work, we report a compact, laser diode bar pumped, single mode, passively Q-switched, Nd +3 :YAP based oscillator, providing TEM 00 output at 1.34 μm, with 0.55 mJ, 730 ps pulses at 100 Hz repetition rate. A compact beam shaping scheme is developed for end pumping of 6 mm long Nd +3 :YAP crystal Fig. 1 (a).
We present a sub-ns (733 ps), high energy (> 0.5 mJ), high peak power (~1 MW), longitudinally-diode pumped, passively Q-switched Nd+3: YAP/V+3: YAG miniature laser oscillator at 100-125 Hz, generating a single mode beam at 1342 nm.
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