Ultra-low-loss Ta_2O_5-core/SiO_2-clad planar waveguides on Si substrates

Abstract

An increasing number of systems and applications depend on photonics for transmission and signal processing. This includes data centers, communications systems, environmental sensing, radar, lidar, and microwave signal generation. Such systems increasingly rely on monolithic integration of traditionally bulk optical components onto the chip scale to significantly reduce power and cost while simultaneously maintaining the requisite performance specifications at high production volumes. A critical aspect to meeting these challenges is the loss of the waveguide on the integrated optic platform, along with the capability of designing a wide range of passive and active optical elements while providing compatibility with low-cost, highly manufacturable processes, such as those found in CMOS. In this article, we report the demonstration of a record low propagation loss of 3 1 dB∕m across the entire telecommunications C-band for a CMOS-compatible Ta 2 O 5 -core∕SiO 2 -clad planar waveguide. The waveguide design, fabrication process, and optical frequency domain reflectometry characterization of the waveguide propagation loss and group index are described in detail. The losses and dispersion properties of this platform enable the integration of a wide variety of linear and nonlinear optical components on-chip, as well as integration with active rare-earth components for lasers and amplifiers and additionally silicon photonic integrated devices. This opens up new integration possibilities within the data communications, microwave photonics, high bandwidth electrical RF systems, sensing, and optical signal processing applications and research communities.

Superconducting nanowire single-photon detectors integrated with tantalum pentoxide waveguides

“…by reducing the length of impedance matching tapers 38 . Ta 2 O 5 further features a wide band gap and lower density of impurities 39 , resulting in significantly lower optical loss at visible and near-infrared wavelengths as compared to other nanophotonic platforms such as silicon nitride (Si 3 N 4 ). Notably, Ta 2 O 5 also offers very attractive material properties for realizing single-photon sources.…”

Photonic-Assisted Scanning Receivers for Microwave Frequency Measurement

“…The other factor was the waveguide propagation loss as the light propagates along the micro-ring resonator, which is around 2.5 dB/cm. Significant reduction of the propagation loss can be realized via adopting a monolithic waveguide of wedge geometry, high-aspect-ratio Si 3 N 4 waveguides, and waveguide based on high-quality silicon oxynitride films [31][32][33][34]. In [31], an optical delay line fabricated on a silicon chip was presented, and it exhibited an average measured waveguide loss of 0.08 ± 0.01 dB/m in long spirals.…”

Integrated Microwave Photonics for Wideband Signal Processing

“…Thanks to the CMOS-compatible fabrication technology which promises a more cost effective, robust and compact solution, delay elements based on various chip-scale platforms have been intensively investigated. In particular, low propagation loss has been demonstrated in optical waveguides of wedge geometry, high-aspect-ratio Si3N4, and high-quality silicon oxynitride films [32][33][34][35][36]. In [32], an optical delay line fabricated on a silicon chip has been presented, exhibiting an average measured waveguide loss of 0.08 ± 0.01 dB/m in long spirals.…”