Room temperature subwavelength metallo-dielectric nanolaser

Press release from Calit2

Nanolaser

First nanoscale laser smaller than the emission wavelength in all three directions. To date these are the smallest lasers demonstrated to lase at room temperature

We demonstrated that by incorporating a silica (silicon dioxide) shield layer between the metal and a semiconductor gain disk and optimizing the silica thickness, the gain threshold of the laser can be substantially reduced such that it is amenable to room temperature operation. The benefit stems from the tendency of the low-index shield to push the electromagnetic mode towards the high-index inner core and away from the metal walls, reducing the mode-metal overlap and hence the Joule loss. The nanolaser integrated with Si will enable efficient generation of light for Si-photonic chip scale integration.

We have demonstrated lasing from devices that are about 1 micron in each direction and provide laser emission at 1. 5 microns which is a record achievement. The devices are fabricated using InGaAsP MQWs grown on InP wafers. The wafer is patterned and etched resulting in cylindrical posts (Fig.1-b), covered with an optimized layer of silica (Fig.1-c), and then covered with a layer of aluminum (Fig. 1-d). The fabrication process can yield arrays of closely packed laser emitters with record emitter pitch while remaining isolated from each other owing to the presence of the metal shield. The narrow emission spectra obtained from a set of lasers and the characteristic slope change in the light-light curve demonstrate lasing at room temperature.

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