Glass Interposer Assisted Edge Coupling to SiN Photonic Integrated Circuits

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Integrated Circuit Design

Background:

• Scaling fiber-to-chip interfaces is crucial for high-performance photonic integrated circuits (PICs).
• Existing solutions face limitations in density and bandwidth, hindering advanced PIC integration.
• A critical bottleneck exists in packaging solutions for dense, high-bandwidth PICs.

Purpose of the Study:

• To present a novel, high-density edge coupling solution for PICs.
• To enable low-loss, simultaneous multichannel coupling to silicon nitride (SiN) chips.
• To address the critical packaging bottleneck in advanced PIC integration.

Main Methods:

• Utilized a glass-based waveguide array to fiber (WAFT) interposer.
• Designed and fabricated SiN edge couplers optimized for WAFT-coupled fibers.
• Characterized the full coupling interface across O and C optical bands.

Main Results:

• Achieved exceptional density of up to 67 input/output (I/O) channels per millimeter.
• Measured low fiber-to-chip coupling loss (CL) per port: 1.55-1.81 dB (TE)/1.55-1.93 dB (TM) in O band and 1.67-1.86 dB (TE)/1.58-1.69 dB (TM) in C band.
• Demonstrated low polarization-dependent loss (PDL) with CL of 1.42-1.62 dB/port at 1310 nm and 1.35-1.83 dB/port at 1550 nm.

Conclusions:

• The WAFT-based edge coupling solution offers a promising approach for scalable PIC integration.
• This method effectively bridges single-mode fibers to SiN chips with mode-field matching.
• The solution addresses a critical packaging bottleneck for high-density, bandwidth-flexible PIC applications.