Efficient light coupling into in-plane semiconductor nanomembrane photonic devices utilizing a sub-wavelength grating...

Area of Science:

• Photonics
• Nanotechnology
• Materials Science

Background:

• Efficient light coupling is crucial for integrated photonic devices.
• Silicon nanomembranes (SiNMs) offer unique properties for advanced photonic applications.
• Existing coupling methods often lack the efficiency required for complex SiNM devices.

Purpose of the Study:

• To demonstrate a subwavelength grating (SWG) coupler for efficient light coupling into in-plane silicon nanomembrane (SiNM) photonic devices.
• To characterize the coupling efficiency and bandwidth of the fabricated SWG coupler.
• To highlight the potential of SWG couplers for enabling novel SiNM-based hybrid photonic devices.

Main Methods:

• Fabrication of a subwavelength grating (SWG) coupler comprising a periodic array of rectangular trenches on a SiNM.
• Transferring the SiNM with the fabricated SWG onto a glass substrate.
• Optical characterization of the SWG coupler at a wavelength of 1555.56 nm to determine coupling efficiency and bandwidth.

Main Results:

• Achieved a coupling efficiency of 39.17% (-4.07 dB) for a 10 µm wide, 17.1 µm long SWG coupler.
• Measured 1 dB and 3 dB bandwidths of 29 nm and 57 nm, respectively.
• Demonstrated low peak efficiency variation (0.26 dB) across five fabricated grating pairs, indicating fabrication consistency.

Conclusions:

• The developed SWG coupler provides a highly efficient method for integrating light into SiNM photonic devices.
• Further improvements in SiNM transfer processes can enhance coupling efficiency.
• This high-efficiency coupling technology paves the way for realizing diverse hybrid photonic devices using nanomembrane technology.