Light-emitting-diode-pumped active Q-switched Nd:YLF laser

Area of Science:

• Laser Physics
• Optoelectronics
• Materials Science

Background:

• Traditional laser pumping methods (laser diodes, lamps) have limitations in spectral matching and efficiency.
• Light-emitting diodes (LEDs) offer a cost-effective and spectrally broad pumping alternative, but their application in lasers requires novel theoretical and design approaches.
• Active Q-switching is a technique to achieve high-peak-power laser pulses.

Purpose of the Study:

• To demonstrate the first active Q-switching laser pumped by a light-emitting diode (LED) using a Neodymium-doped Yttrium Lithium Fluoride (Nd:YLF) crystal.
• To develop a theoretical framework, the effective absorption spectrum, to characterize LED pumping of gain materials.
• To optimize the pumping scheme for efficient energy extraction and high-quality beam output.

Main Methods:

• Utilized an acousto-optic modulator for active Q-switching of the Nd:YLF laser.
• Employed a spectrally broad LED as the pump source, analyzing its unique pumping characteristics.
• Designed a flat-top beam profile for efficient pumping of the Nd:YLF crystal.
• Investigated the effective absorption spectrum concept for LED-band pumping.

Main Results:

• Achieved 165 μJ output energy at 1047 nm from the LED-pumped Nd:YLF crystal with a low peak pump power density (14 W/cm²).
• Successfully realized a TEM00 mode output using acousto-optic Q-switching.
• Obtained a pulse energy of 10.6 μJ with a pulse width of 452 ns in the Q-switched operation.

Conclusions:

• The successful demonstration of an active Q-switching LED-pumped Nd:YLF laser validates the proposed effective absorption spectrum theory.
• This work establishes a new paradigm for developing compact, efficient, and potentially lower-cost laser systems using LED pumping.
• The results highlight the potential of LED pumping for various laser applications requiring specific beam characteristics and pulse formats.