LED-pumped alexandrite laser oscillator and amplifier.

Area of Science:

• Laser Physics
• Materials Science
• Solid-State Lighting

Background:

• Advancements in light-emitting-diode (LED) technology offer new pumping possibilities for solid-state lasers.
• Chromium-doped alexandrite crystals (Cr³⁺:BeAl₂O₄) are promising gain media for tunable laser applications.
• Previous laser systems often relied on less scalable or efficient pumping sources.

Purpose of the Study:

• To develop and demonstrate the first LED-pumped laser oscillator and amplifier using alexandrite crystals.
• To leverage high-power blue LEDs and a Ce:YAG concentrator for efficient optical pumping.
• To characterize the performance of the LED-pumped alexandrite laser in both oscillator and amplifier configurations.

Main Methods:

• Designed and constructed an LED-pumped system using 2200 blue LEDs (450 nm) illuminating a Ce:YAG concentrator.
• The Ce:YAG concentrator delivered 268 mJ at 550 nm to the alexandrite gain medium at 10 Hz.
• Configured the alexandrite crystal as both a free-running oscillator and a multi-pass amplifier.

Main Results:

• Demonstrated an LED-pumped alexandrite laser oscillator producing 2.9 mJ at 748 nm.
• Measured a double-pass small signal gain of 1.28 in the oscillator cavity, matching simulations.
• Achieved amplification of a CW Ti:sapphire laser by a factor of 4 at 750 nm over an 8-pass configuration with a 710-800 nm tuning range.

Conclusions:

• Successfully demonstrated the feasibility of LED pumping for alexandrite lasers, opening new avenues for laser development.
• The Ce:YAG concentrator system provides a scalable and efficient pumping solution for solid-state laser gain media.
• The developed system shows potential for tunable laser applications requiring efficient and compact pumping sources.