Abstract
This paper presents recent results on widely-tunable narrow-linewidth semiconductor lasers using a ring-resonator based mirror as the extended cavity. Two generations of lasers on the heterogeneous Si/InP photonic platform are presented. The first-generation lasers, with a total footprint smaller than 0.81 mm2, showed an intrinsic linewidth of ∼2 kHz over a 40 nm wavelength tuning range across C+L bands. The second-generation lasers using ultra-low loss silicon waveguides and a novel cavity design achieved an intrinsic linewidth below 220 Hz. The lasers also possess an ultrawide wavelength tuning range of 110 nm across three optical communication bands (S+C+L). These are records among all fully integrated semiconductor lasers reported in the literature.
Highlights
L OW noise, widely tunable lasers, with spectral linewidth of kHz level or lower, are in demand by an increasing number of applications, such as coherent communications, LiDAR, optical sensing and spectroscopy [1]–[5]
This paper described the design, fabrication and characterization of narrow-linewidth lasers with wide wavelength tunability, an important class of semiconductor lasers for systems such as LIDAR, microwave photonics, and coherent communications
The first-generation lasers using a dual-ring mirror in standard silicon rib waveguides with propagation loss ∼1.2 dB/cm demonstrate 40 nm wavelength tuning range in C+L bands and Lorentzian linewidth ∼2 kHz
Summary
L OW noise, widely tunable lasers, with spectral linewidth of kHz level or lower, are in demand by an increasing number of applications, such as coherent communications, LiDAR, optical sensing and spectroscopy [1]–[5] Such low noise is only commercially available in solid-state lasers, fiber-based lasers and blazed-gratings or fibers based external cavity lasers. External cavities based on planar light wave circuits (PLC) [12], low loss silicon nitride [13]–[15], and silicon [16], [17] have been demonstrated The drawback regarding these assembled hybrid semiconductor lasers is their limited scalability, as each laser must be individually assembled. We conclude the paper with discussion on future directions for further improving the laser performance
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