Slow-to-fast light using absorption to gain switching in quantum-well semiconductor optical amplifier

Area of Science:

• Optoelectronics
• Quantum-well devices
• Nonlinear optics

Background:

• Semiconductor optical amplifiers are crucial for optical communication systems.
• Controlling the speed of light is essential for advanced optical signal processing and buffering.
• Quantum-well devices offer unique properties for manipulating light-matter interactions.

Purpose of the Study:

• To investigate the use of a room-temperature quantum-well semiconductor optical amplifier for controlling the speed of light.
• To demonstrate tunable slow and fast light phenomena using electrical injection current.
• To explore the potential of this device as a building block for optical buffer systems.

Main Methods:

• Utilizing a quantum-well semiconductor optical amplifier in both absorption and gain regimes.
• Employing coherent population oscillation and four-wave mixing to create material resonance.
• Tuning the material resonance via electrical injection current to control light speed.
• Analyzing the switching between slow and fast light using a four-wave mixing and population oscillation model.

Main Results:

• Achieved tunable optical group delay and advance (slow and fast light) at room temperature.
• Demonstrated control over the speed of light by adjusting electrical injection current.
• Experimentally achieved a 200-degree phase shift at 1 GHz, yielding a 0.56 delay-bandwidth product.
• Validated the slow-to-fast light switching mechanism through experimental observation and theoretical modeling.

Conclusions:

• The developed semiconductor optical amplifier effectively controls light speed for optical buffering applications.
• The device provides a feasible building block for multi-bit optical buffer systems.
• Electrical tuning of material resonance offers a practical method for manipulating light propagation speed in semiconductor devices.