Bidirectional grating coupler based optical modulator for low-loss integration and low-cost fiber packaging

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Devices

Background:

• Optical modulators are crucial components in high-speed optical communication systems.
• Efficient fiber coupling and low insertion loss are key challenges in integrated photonic devices.
• Grating couplers offer a pathway for vertical fiber-to-chip coupling.

Purpose of the Study:

• To propose and demonstrate a novel optical modulator utilizing a bidirectional grating coupler.
• To achieve high performance metrics including low insertion loss and high extinction ratio.
• To evaluate the device's suitability for high-speed data transmission and its tolerance to fiber misalignment.

Main Methods:

• Design and fabrication of a novel optical modulator incorporating a bidirectional grating coupler.
• Characterization of the grating coupler's performance as a fiber coupler and 3-dB splitter.
• Analysis of static characteristics to assess fiber misalignment tolerance.
• 10 Gb/s data transmission experiments with varying fiber launch positions.

Main Results:

• The device demonstrates a low on-chip insertion loss of 5.4 dB (including coupling loss).
• A high on-off extinction ratio exceeding 20 dB was achieved.
• Modulation efficiency was measured between 3-3.84 V·cm.
• Energy efficiency of 8.1 pJ/bit was estimated during 10 Gb/s data transmission.

Conclusions:

• The proposed bidirectional grating coupler-based optical modulator offers efficient vertical fiber coupling and high performance.
• The device exhibits excellent static characteristics and tolerance to fiber misalignment, suitable for practical applications.
• This modulator presents a promising solution for energy-efficient, high-speed optical communication systems.