High efficiency >26 W diode end-pumped Alexandrite laser

Abstract

We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

InP/InGaP quantum-dot SESAM mode-locked Alexandrite laser

“…In addition, more efficient mode locking should be possible by designing QD-SESAMs specifically for Alexandrite laser crystal that has a gain peak around 755 nm wavelength [10,11]. Also, low quantum defect of visible diode pumping [13,14] should lead to efficient and powerful ultrafast Alexandrite oscillators that will be very attractive for various applications including nonlinear frequency conversion [39][40][41][42], multiphoton microscopy [43,44], and ultrafast spectroscopy [45].…”

“…On the other hand, Alexandrite (Cr-doped chrysoberyl BeAl2O4) is another example of vibronic laser crystal [10] that has a wide (~100 nm) wavelength tuning range around 750 nm and high thermal conductivity (similar to Ti:sapphire) [11,12]. Its other advantages are highly polarized output radiation and broad absorption bands that can be used for direct pumping with visible laser diodes [13,14]. Unlike Ti:sapphire, Alexandrite can be directly pumped with red laser diodes because its absorption band covers most of the visible spectral range [10,13].…”

“…Its other advantages are highly polarized output radiation and broad absorption bands that can be used for direct pumping with visible laser diodes [13,14]. Unlike Ti:sapphire, Alexandrite can be directly pumped with red laser diodes because its absorption band covers most of the visible spectral range [10,13]. In addition, its larger στ product [15] presents a prospect of lower laser threshold.…”

“…In addition, its larger στ product [15] presents a prospect of lower laser threshold. Furthermore, a diode-pumped Alexandrite laser was shown to produce >26 W of output power in the continuous wave regime [13] which significantly exceeds output from widely used Ti:sapphire lasers. Despite these advantages, femtosecond laser mode locking was demonstrated only recently and resulted in the generation of 170 fs long pulses from a Kerr-lens mode-locked (KLM) Alexandrite laser [16].…”

Analytical model of tunable Alexandrite lasing under diode end-pumping with experimental comparison

“…Recent advancements in high power red laser diodes has enabled efficient and multi-watt diode pumped operation [6,7]. The benefits of diode pumping include an order of magnitude increase in laser efficiency and the ability to more easily control the delivery of the pump energy to the gain medium, as in end pumping, achieving a better TEM 00 mode overlap [7].…”