Total internal reflection optical switch using the reverse breakdown of a pn junction in silicon.

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Devices
• Integrated Optics

Background:

• Total-internal-reflection (TIR) optical switches are crucial for optical communication networks.
• Existing silicon-based optical switches often face challenges with integration, efficiency, or complex fabrication.
• Developing compact and efficient silicon optical switches remains an active area of research.

Purpose of the Study:

• To demonstrate a novel silicon total-internal-reflection (TIR) optical switch.
• To utilize a simple pn junction for both optical reflection and thermal control.
• To achieve efficient light switching using plasma dispersion and thermo-optic effects.

Main Methods:

• Fabrication of a silicon optical switch with a pn junction integrated between asymmetrically y-branched multimode waveguides.
• Utilizing the plasma dispersion effect of pre-doped carriers for light reflection at rest.
• Employing the thermo-optic effect induced by reverse breakdown of the pn junction to switch light to transmission.
• Characterizing switching operation in a shallow TIR region (1 μm width) with a 6° branch angle.

Main Results:

• Successful demonstration of switching operation in the fabricated silicon optical switch.
• Achieved an extinction ratio of 12 dB.
• Measured an insertion loss of -4.2 dB.
• Required a thermal heating power of 151.5 mW for switching.

Conclusions:

• The proposed pn junction-based silicon optical switch effectively utilizes plasma dispersion and thermo-optic effects for light switching.
• The device demonstrates promising performance metrics, including a good extinction ratio and manageable insertion loss.
• This design offers a simple and potentially scalable solution for integrated silicon photonics applications.