High efficiency wavelength conversion of 10 Gb/s data in silicon waveguides

Area of Science:

• Photonics
• Semiconductor devices
• Nonlinear optics

Background:

• Four-wave mixing (FWM) is a key nonlinear optical process for wavelength conversion.
• Silicon-on-insulator (SOI) waveguides offer a platform for integrated nonlinear optics.
• Nonlinear absorption, particularly two-photon absorption (TPA) induced free-carrier absorption (FCA), limits FWM efficiency in silicon.

Purpose of the Study:

• To achieve efficient wavelength conversion in SOI p-i-n waveguides.
• To mitigate nonlinear absorption losses limiting FWM efficiency.
• To demonstrate high-speed data wavelength conversion in the C-band.

Main Methods:

• Fabrication of silicon rib waveguides with integrated p-i-n diode structures.
• Application of reverse bias to the p-i-n structure to reduce TPA-induced FCA.
• Characterization of wavelength conversion efficiency and bandwidth under various operating conditions (pump power, detuning, bias voltage).

Main Results:

• Achieved a wavelength conversion efficiency of -8.5 dB in an 8 cm waveguide at 40 MW/cm² pump intensity.
• Demonstrated successful wavelength conversion of 10 Gb/s pseudo-random bit sequence data with clear eye diagrams and no waveform distortion.
• Observed a conversion bandwidth exceeding 30 nm for shorter 1.6 cm waveguides.

Conclusions:

• Reverse biasing SOI p-i-n waveguides effectively suppresses nonlinear absorption, enabling efficient FWM.
• This approach is suitable for high-speed optical signal processing and wavelength routing in the C-band.
• The demonstrated technology shows promise for future optical communication systems.