Design of subwavelength-engineered surface grating couplers on a hybrid α-Si/SiN photonic platform

William Fraser; Daniel Benedikovic; Radovan Korcek; Maziyar Milanizadeh; Jens H. Schmid; Pavel Cheben; Winnie N. Ye

doi:10.1117/12.3001539

12 March 2024 Design of subwavelength-engineered surface grating couplers on a hybrid α-Si/SiN photonic platform

William Fraser, Daniel Benedikovic, Radovan Korcek, Maziyar Milanizadeh, Jens H. Schmid, Pavel Cheben, Winnie N. Ye

Proceedings Volume 12889, Integrated Optics: Devices, Materials, and Technologies XXVIII; 128890F (2024) https://doi.org/10.1117/12.3001539
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

The design of a high-efficiency grating coupler for silicon nitride (SiN) photonic integrated circuits is presented. Our devices use a high-index amorphous silicon (α-Si) overlay and subwavelength metamaterial apodization to achieve superior coupling efficiency compared to SiN-only gratings. The high index contrast of the α-Si layer results in increased grating strength, making it possible to radiate more power off-chip within the mode field diameter (MFD) of a standard single mode optical fiber. Simultaneously, through the use of subwavelength grating (SWG) apodization, we shape the radiated field to optimize the overlap with the Gaussian-like profile of the fiber mode at an operating wavelength of 1.31 μm. The overlap is further improved by considering a focalizing scheme, wherein the grating is designed to couple to a fiber placed a certain distance away from the chip. In this configuration, the constraint imposed on the length of the grating by the MFD of the fiber mode is relaxed, allowing for a longer structure that will diffract more power off-chip. By combining the use of an α-Si overlay with SWG apodization and beam focalization, we achieve a coupling efficiency of - 1.3 dB.

Conference Presentation

Citation Download Citation

William Fraser, Daniel Benedikovic, Radovan Korcek, Maziyar Milanizadeh, Jens H. Schmid, Pavel Cheben, and Winnie N. Ye "Design of subwavelength-engineered surface grating couplers on a hybrid α-Si/SiN photonic platform", Proc. SPIE 12889, Integrated Optics: Devices, Materials, and Technologies XXVIII, 128890F (12 March 2024); https://doi.org/10.1117/12.3001539

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