F. Pagliano

Electromechanical tuning of vertically-coupled photonic crystal nanobeams

We present the design, the fabrication and the characterization of a tunable one-dimensional (1D) photonic crystal cavity (PCC) etched on two vertically-coupled GaAs nanobeams. A novel fabrication method which prevents their adhesion under capillary forces is introduced. We discuss a design to increase the flexibility of the structure and we demonstrate a large reversible and controllable electromechanical wavelength tuning (> 15 nm) of the cavity modes.

Waveguide-coupled nanopillar metal-cavity light-emitting diodes on silicon

Nanoscale light sources using metal cavities have been proposed to enable high integration density, efficient operation at low energy per bit and ultra-fast modulation, which would make them attractive for future low-power optical interconnects. For this application, such devices are required to be efficient, waveguide-coupled and integrated on a silicon substrate. We demonstrate a metal-cavity light-emitting diode coupled to a waveguide on silicon. The cavity consists of a metal-coated III–V semiconductor nanopillar which funnels a large fraction of spontaneous emission into the fundamental mode of an InP waveguide bonded to a silicon wafer showing full compatibility with membrane-on-Si photonic integration platforms. The device was characterized through a grating coupler and shows on-chip external quantum efficiency in the 10−4–10−2 range at tens of microamp current injection levels, which greatly exceeds the performance of any waveguide-coupled nanoscale light source integrated on silicon in this current range. Furthermore, direct modulation experiments reveal sub-nanosecond electro-optical response with the potential for multi gigabit per second modulation speeds.

Dynamically controlling the emission of single excitons in photonic crystal cavities

Single excitons in semiconductor microcavities represent a solid state and scalable platform for cavity quantum electrodynamics, potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both single-photon emission and the strong coupling regime have been demonstrated, further progress has been hampered by the inability to control the coherent evolution of the cavity quantum electrodynamics system in real time, as needed to produce and harness charge–photon entanglement. Here using the ultrafast electrical tuning of the exciton energy in a photonic crystal diode, we demonstrate the dynamic control of the coupling of a single exciton to a photonic crystal cavity mode on a sub-nanosecond timescale, faster than the natural lifetime of the exciton. This opens the way to the control of single-photon waveforms, as needed for quantum interfaces, and to the real-time control of solid-state cavity quantum electrodynamics systems.

Anti-stiction coating for mechanically tunable photonic crystal devices

A method to avoid the stiction failure in nano-electro-opto-mechanical systems has been demonstrated by coating the system with an anti-stiction layer of Al2O3 grown by atomic layer deposition techniques. The device based on a double-membrane photonic crystal cavity can be reversibly operated from the pull-in back to its release status. This enables to electrically switch the wavelength of a mode over ~50 nm with a potential modulation frequency above 2 MHz. These results pave the way to reliable nano-mechanical sensors and optical switches.

Deterministic control of radiative processes by shaping the mode field

Quantum dots (QDs) interacting with confined light fields in photonic crystal cavities represent a scalable light source for the generation of single photons and laser radiation in the solid-state platform. The complete control of light-matter interaction in these sources is needed to fully exploit their potential, but it has been challenging due to the small length scales involved. In this work, we experimentally demonstrate the control of the radiative interaction between InAs QDs and one mode of three coupled nanocavities. By non-locally moulding the mode field experienced by the QDs inside one of the cavities, we are able to deterministically tune, and even inhibit, the spontaneous emission into the mode. The presented method will enable the real-time switching of Rabi oscillations, the shaping of the temporal waveform of single photons, and the implementation of unexplored nanolaser modulation schemes.

Integrated spectrometer and displacement sensor based on mechanically tunable photonic crystals

We present a nano-opto-electro-mechanical sensor based on electrostatically tunable double-membrane photonic crystal cavities. We demonstrate free-space and waveguide coupling schemes for the input light, while the readout is provided by an integrated quantum dot photodiode.

Tuneable quantum light from a photonic crystal LED

Pure and deterministic single-photon sources, obtained by coupling a semiconductor quantum dot (QD) to a photonic crystal (PhC) cavity, constitute a key component for quantum photonic integrated circuits (QPICs) [1]. These sources are commonly excited by a laser pump, which involves some practical limitations in scaling the number of integrated cavity-emitter nodes and is hardly compatible with on-chip single-photon detectors. Here, we present the first demonstration of electrical injection of single dot lines coupled to photonic crystal modes. The latter can be electrically re-configured to bring multiple cavity-emitters into energy resonance.

Integrated metal-cavity nanoLEDs in III-V membranes on silicon

We demonstrate the first waveguide-coupled metal-cavity nanoLED in a III-V photonic membrane bonded to a silicon substrate, which operates at telecommunication wavelengths. The device works under electrical injection and was characterized through a grating coupler.

Controlling the emission from single quantum dots with electro-opto-mechanical photonic crystal cavities

We present a device for the spectral reconfiguration of a two-dimensional photonic crystal cavity (PCC) based on parallel semiconductor membranes. The mechanical motion of the slabs introduces a variation in the effective refractive index of the coupled waveguides where the photonic crystal is etched resulting in a shift of the free-space wavelength. Using an integrated electrostatic actuator we demonstrated independent tuning up to 15 nm with less than 6 V bias. We present the electromechanical control of a PCC mode in resonance to single quantum dot (QD) emission lines for the real-time compensation of the spectral mismatch due to the dots inhomogeneity. We discuss the operation of the device at low temperatures (<; 10 K) and we measured the Purcell effect via the electro-mechanical control. A reversible tuning range of 13 nm and a spontaneous emission rate control by a factor of ten has been achieved.