Progress in Blue Diode-Pumped Titanium:Sapphire Regenerative Amplifier at Room Temperature

For most ultrashort pulse applications where pulse durations < 100 fs are needed, Ti:Sapphire laser material is used because of its broadband emission and good thermal properties. These crystals are currently pumped by frequency doubled Nd:YAG lasers at 532 nm, making Ti:Sapphire laser systems complex and expensive. With the progress in development of GaN based blue laser diodes, direct diode-pumped Ti:Sapphire laser oscillators became feasible [1]. However, for blue diode-pumped Ti:Sapphire amplifiers, the thermal load inside the crystal could only be managed with a cryogenic cooling so far [2]. In this work, we demonstrate that by decreasing the pump spot diameter and operating in a pulsed regime, we reduce the overall thermal load [3], [4] inside the crystal and reach a small signal gain> 30 %. This enables amplification at room temperature.

For most ultrashort pulse applications where pulse durations < 100 fs are needed, Ti:Sapphire laser material is used because of its broadband emission and good thermal properties. These crystals are currently pumped by frequency doubled Nd:YAG lasers at 532 nm, making Ti:Sapphire laser systems complex and expensive. With the progress in development of GaN based blue laser diodes, direct diode-pumped Ti:Sapphire laser oscillators became feasible [1]. However, for blue diode-pumped Ti:Sapphire amplifiers, the thermal load inside the crystal could only be managed with a cryogenic cooling so far [2]. In this work, we demonstrate that by decreasing the pump spot diameter and operating in a pulsed regime, we reduce the overall thermal load [3], [4] inside the crystal and reach a small signal gain> 30 %. This enables amplification at room temperature.