Abstract
For optical sensing or biomedical sensing where the light source usually has a stable and narrow linewidth, the design rule of the tunable optical delay line (ODL) can be different from the ODLs for optical communications and buffering. We present here a novel way to tune a racetrack resonator-based ODL by push–pull operation to stabilize the resonant wavelength. Full device simulation that accounts for the thermal tuning effect and the photonic characteristics of the whole integrated device is conducted to verify the characteristics of the tunable ODLs. With the simple racetrack resonator, the group delay can simply be tuned by changing the coupling coefficient of the resonator while the wavelength is stabilized by tuning the racetrack loop. A tuning of hundreds of picoseconds is achievable with a very compact device and small power consumption.
Highlights
Optical delay lines (ODLs) are key components in many applications, such as optical signal processing and buffering in optical networks, beamforming and filtering in microwave photonic systems, biomedical sensing, and 3D light detection and ranging (LiDAR) [1,2,3,4,5,6]
We report reporthere herea anovel novel way tuning group delay of a racetrack-resonator-based
We report here a novel way of tuning the group delay of a racetrack-resonator-based optical line operating the thermal heaterheater at push–pull mode.mode
Summary
Optical delay lines (ODLs) are key components in many applications, such as optical signal processing and buffering in optical networks, beamforming and filtering in microwave photonic systems, biomedical sensing, and 3D light detection and ranging (LiDAR) [1,2,3,4,5,6]. There are two commonly used approaches to tune the SOI-based ODLs: Tuning with thermal heating or carrier-induced effects Both tuning mechanisms change the refractive index of the waveguide and change the phase. Most of the designs are for optical signal processing or buffering In these applications, the critical requirements include a large enough true delay, wide bandwidth, and low higher-order phase variations that will lead to dispersion and signal distortions. The linewidth of laser sources is typically less than a few MHz or even on the order of kHz. a long delay can be realized with a simple resonator by using a design with a higher quality factor and smaller bandwidth. The ODL design demonstrated in this paper can achieve a true delay ranging from tens of picoseconds to hundreds of picoseconds at a stable wavelength
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