Z. Zobenica

Fully tuneable, Purcell-enhanced solid-state quantum emitters

We report the full energy control over a semiconductor cavity-emitter system, consisting of single Stark-tunable quantum dots embedded in mechanically reconfigurable photonic crystal membranes. A reversible wavelength tuning of the emitter over 7.5 nm as well as an 8.5 nm mode shift are realized on the same device. Harnessing these two electrical tuning mechanisms, a single exciton transition is brought on resonance with the cavity mode at several wavelengths, demonstrating a ten-fold enhancement of its spontaneous emission. These results open the way to bring several cavity-enhanced emitters mutually into resonance and therefore represent a key step towards scalable quantum photonic circuits featuring multiple sources of indistinguishable single photons.

Multiple modes of a photonic crystal cavity on a fiber tip for multiple parameter sensing

Measuring resonant wavelengths of different modes of a luminescent semiconductor photonic crystal cavity placed on the tip of an optical fiber is proposed and demonstrated for simultaneous measurement of multiple parameters, and is applied to the measurement of temperature and refractive index in the temperature range of 77-370 K. The operation principle is supported by the finite-element method simulations. The robustness of a simple mounting scheme without adhesives is proven experimentally. The simplicity, extremely small size, and high sensitivity to both refractive index and temperature makes this concept an ideal fiber-optic sensor for a multitude of applications.

Fully-tunable, purcell-enhanced on-chip quantum emitters

We report the all-electrical control over cavity-emitter systems, consisting in Stark-tunable quantum dots embedded in mechanically reconfigurable photonic crystal membranes. Purcell-effect from a single dot is demonstrated at distinct wavelengths.

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.

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.

Single photons from electrically driven reconfigurable photonic crystal cavities (Conference Presentation)

Due to their deterministic nature and efficiency, devices based on quantum dots (QD) are currently replacing traditional single-photon sources in the most complex quantum optics experiments, such as boson sampling protocols. Embedding these emitters into photonic crystal (PhCs) cavities enables the creation of an array of Purcell-enhanced single photons required to build quantum photonic integrated circuits. So far scaling of the number of these cavity-emitters nodes on a single chip has been hampered by practical problems such as the lack of post-fabrication methods to control their relative detuning and the complexity involved with their optical excitation. Here, we present a tuneable single-photon source combining electrical injection and nano-opto-electromechanical cavity tuning. The device consists of a double-membrane electromechanically tuneable PhC structure. A vertical p-i-n junction, hosted in the top membrane, is exploited to inject current in the QD layer and demonstrate a tunable nano LED whose cavity wavelength can be reversibly varied over 15 nanometers by electromechanically varying the distance between membranes. Besides, electroluminescence from single QD lines coupled to PhC cavities is reported for the first time. The measurement of the second-order autocorrelation function from a cavity-enhanced line proves the anti-bunched character of the emitted light. Since electrical injection does not produce stray pump photons, it makes the integration with superconducting single-photon detectors much more feasible. The large-scale integration of such tuneable single-photon sources, passive optics and waveguide detectors may enable the implementation of fully-integrated boson sampling circuits able to manipulate tens of photons.

High-resolution spectral and displacement sensing using nano-opto-electro-mechanical systems(Conference Presentation)

Nanophotonic structures with narrow optical resonances, such as high-quality factor photonic crystal cavities, in principle enable spectral sensing with high resolution. This can also result in high-sensitivity displacement and/or acceleration sensing if a part of the cavity is compliant. However, the control of the resonance and its optical read-out are complex and usually not integrated with the sensing part. In this talk we will introduce a novel nano-opto-electromechanical system (NOEMS), where actuation, sensing and read-out are integrated in the same device. It consists of a double-membrane photonic crystal cavity, where the resonant wavelength is tuned by electrostatically controlling the separation between the membranes. The output current signal provides direct information about either the wavelength of the incident light or the cavity resonance. This nanophotonic sensing system can be employed to measure the spectrum of incident light, to determine the wavelength of a laser line with pm-range resolution, or equivalently to measure tiny displacements.

Tunable cavity-enhanced quantum light sources for integrated quantum photonics

We report the control over the spontaneous emission of energy-tunable quantum emitters embedded in passive waveguide circuits, realized by coupling Stark-tunable quantum dots to electromechanically-compliant photonic crystal molecules.

Electromechanically-tunable nanophotonic cavities

We present the design, fabrication and characterization of double-membrane photonic crystal cavities electromechanically tunable over >10 nm, and their application in integrated quantum photonics.