AlGaN/AlN integrated photonics platform for the ultraviolet and visible spectral range.

Mohammad Soltani,Dirk Englund,Richard Soref,Tomas Palacios

doi:10.1364/oe.24.025415

Abstract

We analyze a photonic integrated circuit (PIC) platform comprised of a crystalline AlxGa1-xN optical guiding layer on an AlN substrate for the ultraviolet to visible (UV-vis) wavelength range. An Al composition of x~0.65 provides a refractive index difference of ~0.1 between AlxGa1-xN and AlN, and a small lattice mismatch (< 1%) that minimizes crystal dislocations at the AlxGa1-xN/AlN interface. This small refractive index difference is beneficial at shorter wavelengths to avoid extra-small waveguide dimensions. The platform enables compact waveguides and bends with high field confinement in the wavelength range from 700 nm down to 300 nm (and potentially lower) with waveguide cross-section dimensions comparable to those used for telecom PICs such as silicon and silicon nitride waveguides, allowing for well-established optical lithography. This platform can potentially enable cost-effective, manufacturable, monolithic UV-vis photonic integrated circuits.

Highlights

Numerous applications stand to benefit from photonic integrated circuits (PICs) in the UV and visible (UV-vis) spectrum, including biochemical sensing, UV-Raman spectroscopy, beam steering, nonlinear optics, and quantum photonics
We analyze how the crystalline AlGaN-on-AlN material platform could be leveraged for UV-vis PICs
In the AlxGa1-xN-on-AlN architecture considered here, an x~0.65 provides a sufficiently high index contrast (~0.1), transparency down to ~260 nm, small lattice mismatch ~1% with potentially manageable low strain at the AlGaN/AlN interface, and single-mode waveguides with easy-to-fabricate dimensions comparable to telecom PICs made of silicon and silicon nitride [19,20]

Summary

Introduction

Numerous applications stand to benefit from photonic integrated circuits (PICs) in the UV and visible (UV-vis) spectrum, including biochemical sensing, UV-Raman spectroscopy, beam steering, nonlinear optics, and quantum photonics. “Determination of the refractive indices of AlN, GaN, and AlxGa1-xN grown on (111) Si substrate,” J. The architectures uses the same AlN platform for both AlGaN electronics and PICs. Table 1 summarizes the properties of AlN and GaN compared to other wide bandgap integrated photonic materials.

Results

Conclusion