High resolution, high channel count mid-infrared arrayed waveguide gratings in silicon.

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Arrayed waveguide gratings (AWGs) are crucial components in wavelength division multiplexing systems.
• Silicon-on-insulator (SOI) technology offers advantages for integrated photonic devices due to its high refractive index contrast and CMOS compatibility.

Purpose of the Study:

• To demonstrate the fabrication and performance of AWGs operating in the mid-infrared (4.7 µm) wavelength range using SOI.
• To evaluate the impact of different channel spacings and device configurations on AWG performance, including crosstalk and insertion loss.

Main Methods:

• Fabrication of AWGs on SOI waveguides with specific silicon and buried oxide layer thicknesses.
• Characterization of multi-channel AWGs with varying channel counts and spacings (50 GHz, 87 GHz, 100 GHz, 170 GHz, 200 GHz).
• Measurement of key performance metrics such as crosstalk, insertion loss, channel peak difference, and thermal drift.

Main Results:

• Demonstrated AWGs with crosstalk levels as low as -32.31 dB and insertion losses of -1.43 dB for eight-channel devices.
• Achieved low crosstalk (-21.67 dB and -24.30 dB) and insertion loss (-4.2 dB and -3.8 dB) for 14- and 16-channel devices, respectively.
• Observed a channel peak difference of 9.3 nm for designed AWGs and a transmission spectrum shift of 0.22 nm/°C with temperature variation.

Conclusions:

• The developed SOI-based AWGs operating at 4.7 µm show excellent performance characteristics suitable for mid-infrared photonic applications.
• The results highlight the potential of SOI technology for realizing complex integrated photonic devices in this spectral region.
• The demonstrated thermal stability and precise channel spacing control are critical for practical device implementation.