Electro-optically tunable single-frequency lasing from neodymium-doped lithium niobate microresonators.

Area of Science:

• Photonics
• Laser Technology
• Materials Science

Background:

• Tunable light sources are essential for applications like ranging and spectroscopy.
• Whispering gallery resonator lasers offer low thresholds and narrow linewidths but often lack reliable tuning.
• Neodymium-doped lithium niobate presents a promising material for addressing tuning limitations.

Purpose of the Study:

• To present a single-frequency laser utilizing a neodymium-doped lithium niobate whispering gallery mode resonator.
• To demonstrate reliable laser tuning through the linear electro-optic effect.
• To ensure single-mode operation by suppressing higher-order transverse modes.

Main Methods:

• Fabrication of a neodymium-doped lithium niobate whispering gallery mode resonator.
• Implementation of a special geometry to suppress higher-order transverse modes.
• Tuning the laser frequency using the linear electro-optic effect with applied voltage.

Main Results:

• Achieved a tuning range of 3.5 GHz with an applied voltage of 68 V.
• Demonstrated frequency modulation capability using a triangular control signal.
• Observed frequency and power stability better than 20 MHz and 6% over 30 minutes.

Conclusions:

• The developed laser provides a stable and tunable light source.
• The concept is compatible with existing lithium niobate photonic platforms for integration.
• This technology advances miniaturized tunable laser devices for various optical applications.