Silicon integrated nanolaser by nanobeam transfer printing

Abstract

In on-chip optical circuit, the small-footprint and the power dissipation of device are most importance feature. Most promising structure that has small-footprint and less power dissipation is nanobeam structure, which became popular in various fields such as cavity optomechanics, optical trapping, sensor, and laser. In specific, nanobeam photonic crystal shown remarkable properties such as high quality factor and small mode volume; advantageous for increasing the sensitivity of sensor and realizing low-threshold laser. How-ever, since silicon itself is poor for gain material, the light source mostly made of III-V semiconductor. Recently, there were several works integrating InGaAsP photonic crystal laser on silicon chip. To bond the InGaAsP on Si substrate, various techniques have been proposed such as molecular bonding and adhesive bonding. Since the adhesive bonding method is robust in interface requirements, it is widely used. However, the adhesive material typically has poor thermal property and it makes hard to achieve continuous wave operation of photonic crystal laser at room temperature. In this paper, we demonstrate the hybridization/integration of InGaAsP nanobeam photonic crystal laser on silica/SOI substrate via impulse-enhanced transfer printing process. By printing the laser device di-rectly on the substrate, wafer-bonding process can be evaded, which makes the fabrication simple. Also, the use of gain material, which is generally expensive, can be minimized with transfer printing process. Using pol-ydimethylsiloxane (PDMS) stamp as transferring medium, the fabricated InGaAsP nanobeam could be re-leased and printed on silica surface. The printed nanobeam laser has physical volume of 4.0x0.58x0.28 μm3 and 10 air-holes in smallest case, and it shown single mode lasing near 1550 nm with pulsed operation in room temperature. Also, in 16 air-hole case, continuous-wave operation has achieved with effective threshold of μW at room temperature. We expec...