Uni-traveling-carrier variable confinement waveguide photodiodes.

Area of Science:

• Photonics and Optoelectronics
• Semiconductor Devices
• Optical Communications

Background:

• Uni-traveling-carrier photodiodes (PDs) are crucial for high-speed optical communication.
• Existing PD designs face challenges in balancing high-power handling and high-speed operation.
• Variable optical confinement is key to optimizing absorption profiles.

Purpose of the Study:

• To demonstrate uni-traveling-carrier waveguide PDs with a variable optical confinement mode size transformer.
• To optimize the absorption profile for both high-power and high-speed performance.
• To present two distinct PD designs and evaluate their performance metrics.

Main Methods:

• Fabrication of uni-traveling-carrier waveguide photodiodes with integrated mode transformers.
• Characterization of optical confinement and light propagation.
• Measurement of key performance parameters including 3-dB bandwidth, saturation current, RF output power, and third-order output intercept point.

Main Results:

• PD A achieved a 3-dB bandwidth of 12.6 GHz with saturation currents of 40 mA at 1 GHz and 34 mA at 10 GHz.
• PD B demonstrated a 3-dB bandwidth of 2.5 GHz and a saturation current exceeding 100 mA at 1 GHz.
• PD B also exhibited a peak RF output power of +19 dBm and a third-order output intercept point of 29.1 dBm.

Conclusions:

• The demonstrated variable optical confinement transformer effectively optimizes absorption for high-power and high-speed PDs.
• The novel PD designs show promising performance for demanding optical communication applications.
• Further research can explore advanced designs for even higher performance.