Quantum photonic devices in single-crystal diamond

Andrei Faraon,Raymond G Beausoleil,Zhihong Huang,David Fattal,Charles Santori,Kai-Mei C Fu,Victor M Acosta

doi:10.1088/1367-2630/15/2/025010

Abstract

Nitrogen–vacancy centers in diamond have outstanding quantum optical properties that enable applications in information processing and sensing. As with most solid-state systems for quantum photonic applications, the great promise lies in the capability to embed them in an on-chip optical network. Here we present basic integrated devices composed of diamond micro-ring resonators coupled to waveguides that are terminated with grating out-couplers. Strong enhancement is observed for the zero-phonon line of nitrogen–vacancy centers coupled to the ring resonance. The zero-phonon line is efficiently coupled from the ring into the waveguide and then scattered out of plane by the grating out-couplers.

Highlights

Nitrogen–vacancy centers in diamond have outstanding quantum optical properties that enable applications in information processing and sensing
The results of this measurement are shown in figure 3(b) where a continuous wave laser diode (NewFocus Velocity) was scanned across a ring resonance that was later coupled to the spectral line of an NV center
We present a design for a grating that scatters out of plane the transverse magnetic (TM) mode in the waveguide, and ∼ 40% of the scattered light can be collected by a microscope objective with numerical aperture NA = 0.6

Summary

Passive measurements of the cavity–waveguide coupling

The optical properties of the device were first characterized via a transmission measurement, where a laser beam was coupled into one of the gratings and the intensity of the light scattered from the other grating was monitored as shown schematically in figure 3(a). The output was sent to a photodetector, which in this case was the CCD of a spectrometer that was later used to measure the signal from NV centers coupled to the resonator. The results of this measurement are shown in figure 3(b) where a continuous wave laser diode (NewFocus Velocity) was scanned across a ring resonance that was later coupled to the spectral line of an NV center. A similar ring uncoupled to the waveguide had a quality factor of Quncoupled = 12 000, which indicates that the device operates close to the criticalcoupling regime (Qcoupled = Quncoupled/2) where 100% contrast is expected

Low-temperature spectroscopy of nitrogen–vacancy centers

Conclusion