Optical gyroscopes, reflection mirrors, wavelength interleavers and
filters using Sagnac interference in integrated photonics
Abstract
As a fundamental optical approach to interferometry, Sagnac interference
has been widely used for reflection manipulation, precision
measurements, and spectral engineering in optical systems. Compared to
other interferometry configurations, it offers attractive advantages by
yielding a reduced system complexity without the need for phase control
between different pathways, thus offering a high degree of stability
against external disturbance and a low wavelength dependence. The
advance of integration fabrication techniques has enabled chip-scale
Sagnac interferometers with greatly reduced footprint and improved
scalability compared to more conventional approaches implemented by
spatial light or optical fiber devices. This facilitates a variety of
integrated photonic devices with bidirectional light propagation,
showing new features and capabilities compared to
unidirectional-light-propagation devices such as Mach-Zehnder
interferometers (MZIs) and ring resonators (RRs). Here, we present our
latest results for functional integrated photonic devices based on
Sagnac interference. We outline the theory of integrated Sagnac
interference devices with comparisons to other integrated photonic
building blocks such as MZIs, RRs, photonic crystal cavities, and Bragg
gratings. We present our latest results for Sagnac interference devices
realized in integrated photonic chips, including reflection mirrors,
optical gyroscopes, basic filters, wavelength (de)interleavers, and
optical analogues of quantum physics.