Heterogeneously integrated microdisk lasers for optical interconnects and optical logic

Abstract

Optical interconnect and optical packet switching systems could take advantage of small footprint, low power lasers and optical logic elements. Microdisk lasers, with a diameter below 10µm and fabricated in InP membranes with a high index contrast, offer this possibility at the telecom wavelengths. The lasers are fabricated using heterogeneous integration of InP membranes on silicon-on-insulator (SOI) passive waveguide circuits, which allows to combine the active elements with compact, high-index contrast passive elements. The lasing mode in such microdisk lasers is a whispering gallery mode, which can be either in the clockwise (CW) or counter clockwise direction (CCW) or in both. The coupling to the SOI wire waveguides is through evanescent coupling. Predefined, unidirectional operation can be achieved by terminating the SOI wires at one end with Bragg gratings. For all-optical flip-flops, the laser operation must be switchable between CW and CCW, using short optical pulses. Unidirectional operation in either direction is only possible if the coupling between CW and CCW direction is very small, requiring small sidewall surface roughness, and if the gain suppression is sufficiently large, requiring large internal power levels. All-optical flip-flops based on microdisk lasers with diameter of 7.5µm have been demonstrated. They operate with a CW power consumption of a few mW and switch in 60ps with switching energies as low as 1.8fJ. Operation as all-optical gate has also been demonstrated. The surface roughness is limited through optimized etching of the disks and the large internal power is obtained through good heat sink.

Quantum diamond chip under network optical control

“…After interaction with the MR photons are removed from an opposite end of the fiber and go to an optoelectronic converter (for example, CCD), which transforms a light signal into an electric one. In order to remove the photons into the fiber more efficiently, one sometimes creates a diffraction grating at the ends of the waveguide [26,31]. A wavelength dependence of the transmission of the photons feeding the waveguide has minima at the frequencies corresponding to the eigen-frequencies of the MR.…”

“…So the principle of a laser operation, developed by the authors of [31] was based on the photon generation by InP microdisk of 3.75 μm radius, which was located on the plate fabricated by the "silicon on insulator" (SOI) technology. A 100 nm buffer polymer layer between the MR and the plate was deposited for a reliable adhesion.…”

“…The design of the chip, wherein a MR and a waveguide are integrated in a single crystal, may be applied in various optical devices such as optical parametric oscillators, generating a set of discrete photonic lines (comb) [45][46][47], lasers and logic elements of computing devices [31,48]. So the principle of a laser operation, developed by the authors of [31] was based on the photon generation by InP microdisk of 3.75 μm radius, which was located on the plate fabricated by the "silicon on insulator" (SOI) technology.…”