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Although Sc doped AlN (ScAlN) has been used extensively in micro-electro-mechanical systems (MEMS) devices and more recently in optical devices, there have not been thorough studies of its intrinsic optical losses. Here we explore the optical losses of the Sc0.30Al0.70N waveguide system by observing racetrack resonator waveguide quality factors. Using a partial physical etch, we fabricate waveguides and extract propagation losses as low as 1.6 ± 0.3 dB/cm at wavelengths around 1550 nm, mostly dominated by intrinsic material absorption from the Sc0.30Al0.70N thin film layer. The highest quality factor of the resonators was greater than 87,000. The propagation loss value is lower than any value previously published and shows that this material can be broadly used in optical modulators without significant loss.
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Methods to achieve ultra-high quality factor silicon nitride resonators
On-chip resonators are promising candidates for applications in a wide range of integrated photonic fields, such as communications, spectroscopy, biosensing, and optical filters, due to their compact size, wavelength selectivity, tunability, and flexible structure. The high quality (Q) factor is a main positive attribute of on-chip resonators that makes it possible for them to provide high sensitivity, narrow bandpass, and low power consumption. In this Tutorial, we discuss methods to achieve ultra-high Q factor on-chip resonators on a silicon nitride (Si3N4) platform. We outline the microfabrication processes, including detailed descriptions and recipes for steps such as deposition, lithography, etch, cladding, and etch facet, and then describe the measurement of the Q factor and methods to improve it. We also discuss how to extract the basic loss limit and determine the contribution of each loss source in the waveguide and resonator. We present a modified model for calculating scattering losses, which successfully relates the measured roughness of the waveguide interface to the overall performance of the device. We conclude with a summary of work done to date with low pressure chemical vapor deposition Si3N4 resonator devices, confinement, cross-sectional dimensions, bend radius, Q factor, and propagation loss.
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- Award ID(s):
- 1936345
- PAR ID:
- 10594250
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- APL Photonics
- Volume:
- 6
- Issue:
- 7
- ISSN:
- 2378-0967
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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