Waveplate-free electro-optic Q-switch enabled by a relaxor-PbTiO₃ crystal

Area of Science:

• Materials Science
• Optics and Photonics
• Solid State Physics

Background:

• Relaxor ferroelectric crystals, specifically 0.21PIN-0.47PMN-0.32PT (PIN-PMN-32PT), are recognized for their high-performance electro-optic (EO) properties.
• Their application in practical Q-switching systems, however, remains largely unexplored.

Purpose of the Study:

• To demonstrate the first waveplate-free EO Q-switched laser utilizing a PIN-PMN-32PT crystal.
• To explore the potential of relaxor ferroelectric crystals in compact and efficient laser systems.

Main Methods:

• Thermo-optic tuning of the intrinsic birefringence of the PIN-PMN-32PT crystal to achieve quarter-wave phase retardation.
• Integration of the crystal into a diode-pumped Nd:YAG laser cavity without external compensation optics.
• Characterization of laser performance, including pulse energy, duration, and repetition rate.

Main Results:

• Successful demonstration of a waveplate-free EO Q-switched Nd:YAG laser using a 1-mm-long PIN-PMN-32PT crystal.
• The device operated at a sub-kilovolt voltage due to the crystal's ultrahigh EO coefficient (r33 ≈ 900 pm/V).
• Achieved laser pulses with 790 μJ energy, 4.1 ns duration, and a 1 kHz repetition rate.

Conclusions:

• Relaxor ferroelectric crystals are a promising material for developing compact, low-voltage EO Q-switches.
• The waveplate-free design simplifies laser cavity construction and enhances practicality.
• This work paves the way for advanced EO Q-switching applications.