Monolithic integrated InP distributed bragg reflector (DBR) lasers on (001) silicon
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-01-01 |
| Journal | Ghent University Academic Bibliography (Ghent University) |
| Authors | Bin Tian, Zhechao Wang, Marianna Pantouvaki, Weiming Guo, P. Absil |
| Institutions | Imec the Netherlands, Ghent University |
Abstract
Section titled “Abstract”Silicon Photonics more and more is considered as a competitive platform for building complex photonic ICs, applicable in various fields, but the lack of a practical on-chip integrated compact, high-yield and electricallydriven laser source remains a major bottleneck. Due to its indirect bandgap, silicon itself is a poor light emitter. Therefore, new materials such as Germanium, III-V compounds and rare earth doped nanocrystals are being investigated and laser operation from hybrid III-V lasers 1, monolithic Germanium lasers 2 and monolithic IIIV nanowire lasers 3 has been demonstrated. While III-V provides generally better performance, realizing monolithically integrated in-plane lasers that can be integrated with other waveguide circuits remains extremely challenging. In this paper, using a selective area growth technique originally developed for realizing nextgeneration ultrafast electronic transistors, we demonstrate a room temperature operating monolithic integrated inplain InP DBR laser grown on a standard 300mm (001)-silicon substrate. Conventional approaches for growing III-V compounds on silicon require a micrometers-thick buffer to cope with the large lattice mismatch and thermal expansion coefficient difference between silicon and III-Vs. In our work, InP waveguides were selectively grown inside narrow trenches defined by a Shallow-Trench-Isolation (STI) method 4 and V-groove etching. The transmission electron microscope (TEM) image shown in Fig. 1a shows that the InP-material is of high crystalline quality except for the 20nm buffer layer located at the InP-Si interface. Following the epitaxy, we defined first order Bragg gratings (165 nm period, 60 nm etching depth, and 50% Duty Cycle) on top of the diamond-shape InP-waveguides using electron beam lithography (EBL) and plasma etching. Next, the silicon substrate beneath the InP was removed using a selective dry etch process to prevent leakage of the optical field (Fig. 1b). For characterization, 7 ns pump pulses from a 532 nm Nd:YAG nanosecond pulsed laser are delivered to the sample in a uniform rectangular area covering a single cavity. After being scattered by the second order grating located at one end of the DBR laser, the laser emissions is collected by a 50x, 0.65 numerical aperture (NA) objective and measured through a 1⁄4 m monochromator. The single mode spectrum in Fig. 1c and the S-shaped light-light curve convincingly show the devices exhibit indeed laser operation. Efficiencies of more than 5% and high reproducibility of these results over multiple devices and multiple wafers has been demonstrated. The top-down integration process, high yield and high controllability together with the in-plane laser configuration, thin buffer layer and selective area process make this device highly promising as a source for future photonic ICs.
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”- DOI: None