Slow light in a semiconductor waveguide at gigahertz frequencies

Area of Science:

• Optoelectronics
• Semiconductor devices
• Photonics

Background:

• Controlling the speed of light is crucial for advanced optical communication and computing.
• Previous methods for light slowing often required cryogenic temperatures or complex setups.
• Semiconductor waveguides offer a promising platform for integrated photonic devices.

Purpose of the Study:

• To experimentally demonstrate and model significant light slowdown in a semiconductor waveguide at room temperature.
• To investigate methods for controlling the group velocity of light all-optically and electrically.
• To analyze the fundamental limitations of light slowdown based on coherent population oscillations.

Main Methods:

• Experimental demonstration of light slowdown in a 100 micrometer semiconductor waveguide.
• Utilizing coherent population oscillations (CPO) for light modulation.
• Applying both all-optical control and electrical bias voltage for group velocity manipulation.
• Developing a semi-analytical model incorporating CPO and propagation effects.

Main Results:

• Achieved a factor of three light slowdown at room temperature.
• Demonstrated control of group velocity via optical and electrical means.
• Verified experimental results with a derived semi-analytical model.
• Identified carrier lifetime as a key factor limiting achievable delay.

Conclusions:

• Significant light slowdown is achievable in semiconductor waveguides at room temperature and high frequencies.
• Coherent population oscillations provide a viable mechanism for light slowdown control.
• Carrier lifetime presents a fundamental limitation for CPO-based light delay applications.
• The developed model accurately predicts experimental outcomes and aids in understanding limitations.