Shao-Shuai Sui

Mode Investigation for Hybrid Microring Lasers With Sloped Sidewalls Coupled to a Silicon Waveguide

Hybrid AlGaInAs/InP microring lasers with sloped sidewalls coupled to a silicon waveguide are investigated numerically and experimentally. The mode field distribution deviations for the microring resonator with the sloped sidewalls at different tilting angles are simulated by a 3-D finite-difference time-domain technique. Obvious enhancements of output coupling to the silicon waveguide and the active region optical confinement factor can be expected as the microresonator has a trapezoidal shape. A hybrid microring laser with a radius of 19 μm and a width of 2 μm is fabricated with the laser wafer bonded on a silicon-on-insulator wafer using the divinylsiloxane-benzocyclobutene (DVS-BCB) adhesive bonding technique. Continuous-wave electrically injected operation is realized at a tilting angle of -6° with the threshold currents of 7.8 and 9 mA at 12 °C and 22 °C. In addition, for a hybrid microring laser with a radius of 29 μm and a ring width of 2.5 μm, continuous-wave electrical operation up to 50 °C is achieved.

Sixteen-Wavelength Hybrid AlGaInAs/Si Microdisk Laser Array

We report a sixteen-wavelength hybrid AlGaInAs/InP microdisk laser array adhesively bonded on a silicon-on-insulator wafer. Sixteen-wavelength lasing from one underlying waveguide is achieved with the channel wavelength spacing of ~3 nm at pulsed injection currents. We experimentally study the influence of thermal effects on the mode wavelength adjusting, and obtain the thermal resistance of ~4 K/mW for the microdisk with a radius of ~9 μm. The thermal characteristics are analyzed using the finite-element method, and a p-electrode metal thermal shunt is proposed to achieve continuous-wave operation.

Mode selection in square resonator microlasers for widely tunable single mode lasing.

Mode selection in square resonator semiconductor microlasers is demonstrated by adjusting the width of the output waveguide coupled to the midpoint of one side. The simulation and experimental results reveal that widely tunable single mode lasing can be realized in square resonator microlasers. Through adjusting the width of the output waveguide, the mode interval of the high-Q modes can reach four times of the longitudinal mode interval. Therefore, mode hopping can be efficiently avoided and the lasing wavelength can be tuned continuously by tuning the injection current. For a 17.8-μm-side-length square microlaser with a 1.4-μm-width output waveguide, mode-hopping-free single-mode operation is achieved with a continuous tuning range of 9.2 nm. As a result, the control of the lasing mode is realized for the square microlasers.

Locally deformed-ring hybrid microlasers exhibiting stable unidirectional emission from a Si waveguide

We propose and demonstrate a locally deformed-ring (LDR) hybrid microlaser to realize stable unidirectional emission from a silicon waveguide. The coupled modes eliminate the competition between clockwise (CW) and counter-clockwise (CCW) modes, and the highly unidirectional characteristics are achieved with an enhanced mode quality factor based on a locally deformed notch in the LDR resonator. Using a divinylsiloxane-benzocyclobutene bonding technique, a LDR hybrid microlaser is fabricated vertically coupled to a silicon waveguide with a radius of 20 μm, a ring width of 4 μm and a notch width of 500 nm. The threshold current is 7 mA, and single-mode lasing is achieved with the side-mode suppression ratio of 27 dB. Nearly total unidirectional output from the CCW direction of a Si waveguide is demonstrated with a unidirectional ratio of 0.053.

Hybrid spiral-ring microlaser vertically coupled to silicon waveguide for stable and unidirectional output

A hybrid spiral-ring laser vertically coupled to a silicon waveguide is demonstrated to achieve stable and unidirectional output theoretically and experimentally. The mode competition between clockwise (CW) and counter-clockwise (CCW) modes is eliminated due to the mode coupling in a spiral resonator. The simulation results indicate that the CCW and CW direction traveling waves are dominant components, respectively, for the spiral resonator without and with an output waveguide. A hybrid AlGaInAs/Si spiral-ring laser is designed and fabricated vertically coupled to a silicon waveguide. For a spiral-ring laser with a radius of 30 μm and a ring width of 5 μm, the continuous-wave lasing threshold of 9.5 mA is obtained with the threshold current density of 1.1  kA/cm(2) at a temperature of 285 K. The output power fluctuations due to the mode competition between CW and CCW modes are eliminated. The output power from CCW direction is five times that from CW direction.

Hybrid AlGaInAs/Si Fabry–Pérot lasers with near-total mode confinements

We have proposed and demonstrated hybrid AlGaInAs/Si Fabry–Perot (FP) lasers, with the FP cavity facet covered by the p-electrode metal for enhancing mode confinement. Continuous-wave lasing is obtained at room temperature with a threshold current of 45 mA for the hybrid FP laser with a cavity length of 415 μ m and a width of 7 μ m. Near-field optical microscope images indicate an efficient output emission from the underneath evanescently-coupled silicon waveguide. Furthermore, single-mode lasing with a side-mode suppression-ratio of 29 dB and a threshold current of 16 mA is realized for the 150 μ m-long hybrid FP laser.

Hybrid Deformed-Ring AlGaInAs/Si Microlasers With Stable Unidirectional Emission

Hybrid deformed-ring microlasers are investigated to realize stable unidirectional emission from a silicon waveguide. Based on numerical simulations of a finite-element technique, we compare directional emission characteristics for spiral microring lasers and locally deformed microring lasers with a notch or a protruded notch. The mode coupling can eliminate mode competition between clockwise (CW) and counterclockwise (CCW) propagating modes and result in better stable unidirectional emission for locally deformed microring lasers with a notch. For a hybrid spiral-ring microlaser with a radius of 30 μm and a ring width of 5 μm, we obtain the output power from the CCW direction as five times as that from the CW direction. The output power from CCW direction as nineteen times as that from CW direction is realized for a deformed-ring microlaser with a radius of 20 μm, a ring width of 4 μm, and a protruded notch of 500 nm.