Nanophotonic devices have gained attention as promising solutions for all-optical image processing. These filters are of subwavelength size and carry potential to address limitations of current image processing technology including processing speed, energy requirements as well as size. We present results demonstrating the use of thin-film absorbers and metasurfaces to real-time detection of edges in images and the visualisation of phase objects including human cancer cells. We discuss the extension of these approaches to implement tuneable devices using phase-change materials and graphene. These approaches have potential for integration into ultra-compact mobile medical diagnostic tools, as well as remote sensing systems.
Unidirectional transmission is a fundamental function in signal processing. In electronic systems, simple semiconductor p–n diodes provide one-way transmission for electrical signals. In the optical domain, however, achieving one-way transmission is difficult because it requires breaking the time-reversal symmetry of light–matter interaction. Previously, magneto-optic effects have been successfully utilized to break the reciprocity of light–matter interaction. Here, we propose a meta-optic diode that supports nonreciprocal light transmission through excitation of asymmetric quasi-bound waves. The meta-optic diode consists of an ultrathin dielectric slab, patterned with two types of subwavelength resonator arrays. The proposed approach is based on the lifetime engineering of the resonant modes in the arrays and the inherent Kerr nonlinearity of the dielectric slab.
Optical Metasurfaces – planarized patterned devices with thickness smaller than or comparable to the operational wavelength – can engineer the light wavefront beyond the limitations of natural materials, and they offer novel opportunities for optical technologies. I will discuss our recent efforts in the design, optimization, fabrication and characterization of dielectric and metallic metasurfaces enabling different nonlinear functionalities, such as nonreciprocal wave propagation, power limiters, efficient SHG generation, and beam steering. I will discuss the main potential and challenges of current approaches and provide an outlook on possible future directions.
We have recently demonstrated that mid-infrared saturable-absorber mirrors and optical power limiters can be constructed using the concept of intersubband polaritonic metasurfaces – devices in which intersubband transitions in a semiconductor heterostructure are strongly coupled with optical modes in nanoresonators. Our original demonstration produced only relatively small (~20%) variation in reflection between low and high intensity illumination. We have now optimized the metasurface design, relying on a GaAsSb-InGaAs heterostructure that provides narrower-linewidth intersubband transitions, increased doping density, and utilized transitions between excited states to significantly improve the experimentally-measured reflectivity contrast, which now spans from 80% to 10% for different illumination intensities.
Optical Metasurfaces – planarized patterned devices with thickness smaller than or comparable to the operational wavelength – can engineer the light wavefront beyond the limitations of natural materials, and they offer novel opportunities for optical technologies. I will discuss our recent efforts in the design, optimization, fabrication and characterization of all-dielectric high-index-contrast metasurfaces enabling different linear and nonlinear functionalities, such as analog image processing, efficient displays for augmented reality and nonreciprocal wave propagation. I will discuss the main potentials and challenges of current approaches and provide an outlook on possible future directions.
Nonlinear metasurfaces based on coupling of intersubband transitions in n-doped semiconductor heterostructures with optical modes in nanoresonators provide the largest known second-order nonlinear response in condensed matter systems in the mid-infrared spectral range. However, these giant nonlinearities are only present at relatively low pumping intensities which limits the maximum achievable frequency conversion efficiency. We experimentally investigate a new nonlinear intersubband metasurface design for second harmonic generation based on two-level nonlinear intersubband system that provides high nonlinearity combined with significantly reduced intensity saturation compared to the intersubband metasurfaces based on three-level intersubband systems demonstrated so far.
In this talk, we discuss our recent experimental efforts on nanostructured metasurfaces to manipulate the optical wavefront using advanced lithographic techniques. In the talk, we will discuss their functionalities for augmented reality, wavefront structuring and control, filtering, spectrometry, polarimetry, and others. We will also discuss the opportunities and challenges to scale these nanostructured surfaces to larger dimensions using alternative fabrication techniques.
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.
A prototypical experiment in cavity quantum electrodynamics involves controlling the light-matter interaction by tuning the frequency of a cavity mode in- and out-of resonance with the frequency of a quantum emitter,1-3 while the field amplitude is generally unaltered. The opposite situation, where one perturbs the spatial pattern of a cavity mode without changing its frequency, has been considered only recently in a few works.4, 5 Changing the amplitude of the field at the emitter's position has important applications, at it allows a real-time control of the light-matter coupling rate, and therefore a direct control of processes such as spontaneous emission and Rabi oscillations. In view of this large potential, in this paper we discuss general design principles that allow obtaining large variations of the electromagnetic field, without change of the frequency, upon an external perturbation of the cavity. We showcase the application of these rules to two photonic structures, a single Fabry-Perot cavity and a coupled three-cavity system. As showed by our analysis and by the examples provided, a small frequency spacing between the modes of the unperturbed cavity is an important requirement to obtain large field variations upon small perturbations. In this regard, a coupled-cavity system, where the frequency spacing is controlled by the interaction rates between the single cavities, constitutes the most promising system to achieve large modulations of the field amplitude.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.