Enhanced gain in O-band quantum-dot semiconductor optical amplifier based on a dual-pass amplification scheme

Area of Science:

• Optoelectronics
• Materials Science
• Telecommunications

Background:

• Quantum dot (QD)-based semiconductor optical amplifiers (SOAs) are essential for advanced optical communication networks.
• Existing SOAs face limitations in gain and power efficiency, hindering network performance.
• High-gain amplifiers are needed to reduce light source power requirements and eliminate complex cooling systems.

Purpose of the Study:

• To demonstrate a high-gain 1.3 µm QD SOA utilizing a novel dual-pass configuration.
• To evaluate the performance enhancements offered by the dual-pass design compared to a single-pass configuration.
• To investigate the impact of p-type modulation doping on amplifier gain and bandwidth at elevated temperatures.

Main Methods:

• Fabrication of a 1.3 µm QD SOA.
• Implementation of a dual-pass optical configuration for signal amplification.
• Characterization of small-signal gain, saturation output power, and 3-dB bandwidth under varying conditions, including elevated temperatures (80 °C).

Main Results:

• Achieved a record small-signal gain of 44.5 dB and a saturation output power of 12 dBm.
• The dual-pass configuration increased output power by 8.5 times and maximum gain by 11 dB over the single-pass design at 300 mA bias current.
• Demonstrated a maximum double-pass gain of 21.1 dB with a 20 nm 3-dB bandwidth at 80 °C using p-type modulation doping.

Conclusions:

• The proposed dual-pass QD SOA configuration significantly enhances gain and output power, crucial for future optical networks.
• P-type modulation doping enables high-gain operation even at elevated temperatures, reducing the need for cooling.
• QD-based SOAs offer a promising, energy-efficient solution for expanding fiber-optic communication capacity and performance.