Compact silicon photonic hybrid ring external cavity (SHREC)/InGaSb-AlGaAsSb wavelength-tunable laser diode operating from 1881-1947†nm.

In recent years, the 2 µm waveband has been gaining significant attention due to its potential in the realization of several key technologies, specifically, future long-haul optical communications near the 1.9 µm wavelength region. In this work, we present a hybrid silicon photonic wavelength-tunable diode laser with an operating range of 1881-1947 nm (66 nm) for the first time, providing good compatibility with the hollow-core photonic bandgap fiber and thulium-doped fiber amplifier. Room-temperature continuous-wave operation was achieved with a favorable on-chip output power of 28 mW. Stable single-mode lasing was observed with side-mode suppression ratio up to 35 dB. Besides the abovementioned potential applications, the demonstrated wavelength region will find critical purpose in H2O spectroscopic sensing, optical logic, signal processing as well as enabling the strong optical Kerr effect on Si.

Ultra-broadband on-chip twisted light emitter for optical communications.

On-chip twisted light emitters are essential components of orbital angular momentum (OAM) communication devices1, 2. These devices address the growing demand for high-capacity communication systems by providing an additional degree of freedom for wavelength/frequency division multiplexing (WDM/FDM). Although whispering-gallery-mode-enabled OAM emitters have been shown to possess some advantages3, 4, 5, such as compactness and phase accuracy, their inherent narrow bandwidths prevent them from being compatible with WDM/FDM techniques. Here, we demonstrate an ultra-broadband multiplexed OAM emitter that utilizes a novel joint path-resonance phase control concept. The emitter has a micron-sized radius and nanometer-sized features. Coaxial OAM beams are emitted across the entire telecommunication band from 1,450 to 1,650 nm. We applied the emitter to an OAM communication with a data rate of 1.2 Tbit/s assisted by 30-channel optical frequency combs (OFCs). The emitter provides a new solution to further increase capacity in the OFC communication scenario.

Compact microring resonators integrated with grating couplers working at 2 µm wavelength on silicon-on-insulator platform.

Compact all-pass and add-drop microring resonators (radius=10 µm) integrated with grating couplers working at 2 µm wavelength are designed, fabricated, and characterized on a commercial 340-nm-thick-top-silicon silicon-on-insulator platform. They are suitable for high-volume integrated optical circuits at 2 µm wavelength as the fabrication process involved are uncomplicated and complementary metal-oxide-semiconductor (CMOS)-process compatible, thus making them more convenient to be utilized. The performance of the grating couplers, based on four most important parameters, has been simulated and optimized. The simulation and experimental results of grating couplers show the lowest coupling loss of 4.5 dB and 6.5 Db, respectively. By utilizing the grating couplers to couple light in and out from the chip, the designed microring resonators have been tested. The experimental results of microring resonators show that an extinction ratio of 12 dB and a quality factor of 11,200 can be achieved. To the best of our knowledge, this is thus far the smallest microring resonator ever demonstrated at this wavelength.

Ultra-compact MMI-based beam splitter demultiplexer for the NIR/MIR wavelengths of 1.55 µm and 2 µm.

Based on restricted interferences mechanism in a 1x2 MMI beam splitter, we theoretically investigate and experimentally demonstrate an ultra-compact MMI-based demultiplexer for the NIR/MIR wavelengths of 1.55 µm and 2 µm. The device is fabricated on 340 nm SOI platform, with a footprint of 293x6 µm2. It exhibits extremely low insertion losses of 0.14 dB and 1.2 dB at the wavelengths of 1.55 µm and 2 µm, respectively, with contrasts of approximately 20 dB for both wavelengths, and a cross-talk of 18.83 dB.

Electromagnetically induced transparency-like effect in microring-Bragg gratings based coupling resonant system.

An all-pass microring-Bragg gratings (APMR-BG) based coupling resonant system is proposed and experimentally demonstrated to generate electromagnetically induced transparency (EIT)-like transmission for the first time. The coupling between two light path ways in the micro-ring resonator and the Fabry-Pérot (F-P) resonator formed by two sections of Bragg gratings gives rise to the EIT-like spectrum. This system has the advantage of a small footprint consisting of only one microring resonator and one bus waveguide with Bragg gratings. It also has a large fabrication tolerance as the overlap requirement between the resonance wavelengths of the microring and the F-P resonator is more relaxed. The two most important properties of the EIT-like transmission namely the insertion loss (IL) and the full-width-at-half-maximum (FWHM) have been analytically investigated by utilizing the specially developed model based on the transfer matrix method. The APMR-BG based coupling resonant system was fabricated on a silicon-on-insulator (SOI) platform. The EIT-like transmission with an extinction ratio (ER) of 12 dB, a FWHM of 0.077 nm and a quality factor (Q factor) of 20200 was achieved, which agree well with the simulated results based on our numerical model. A slow light with a group delay of 38 ps was also obtained.