Spatial light modulators (SLMs) are central to numerous applications ranging from high-speed displays to adaptive optics, structured illumination microscopy, and holography. After decades of advances, SLM arrays based on liquid crystals can now reach large pixel counts exceeding 10^6 with phase-only modulation with a pixel pitch of less than 10 μm and reflectance around 75%. However, the rather slow modulation speed in such SLMs (below hundreds of Hz) presents limitations for many applications. Here we propose an SLM architecture that can achieve high pixel count with high-resolution phase-only modulation at high speed in excess of GHz. The architecture consists of a tunable two-dimensional array of vertically oriented, one-sided microcavities that are tuned through an electro-optic material such as barium titanate (BTO). We calculate that the optimized microcavity design achieves a π phase shift under an applied bias voltage below 10 V, while maintaining nearly constant reflection amplitude. As two model applications, we consider high-speed 2D beam steering as well as beam forming. The outlined design methodology could also benefit future design of spatial light modulators with other specifications (for example amplitude modulators). This high-speed SLM architecture promises a wide range of new applications ranging from fully tunable metasurfaces to optical computing accelerators, high-speed interconnects, true 2D phased array beam steering, and quantum computing with cold atom arrays.
We experimentally demonstrate tunable, highly-stable frequency combs with high repetition-rates using a single, charge injection based silicon PN modulator. In this work, we demonstrate combs in the C-band with over 8 lines in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also demonstrate through simulations the potential for bandwidth scaling using an optimized silicon PIN modulator. We find that, the time varying free carrier absorption due to carrier injection, an undesirable effect in d…
Complex optical systems such as high-quality microcavities enabled by advanced lithography and processing techniques paved the way to various light-matter interactions (LMI) studies. Without lattice-matching constraints in epitaxy, coating techniques or shaky open cavity constructions, sub-micrometer-precise lithographic development of a polymer photoresist paves the way to polymer microcavity structures for various spectral regions based on the material's transparency and the geometrical sizes. We introduce a new approach based on 3D nanowriting in photoresist, which can be employed to achiev…
Raman lasers based on bulk diamond are a valuable resource for generating coherent light in wavelength regimes where no common laser diodes are available. Nevertheless, the widespread use of such lasers is limited by their high threshold power requirements on the order of several Watts. Using on-chip microresonators, a significant reduction of the lasing threshold by more than two orders of magnitude has been shown. However, these resonators lack a continuous tuning mechanism and, mainly due to fabrication limitations, their implementation in the visible remains elusive. Here, we propose a pla…
Spectral manifestations of hybrid Tamm-microcavity modes in a 1D photonic crystal bounded with a silver layer and containing a nematic liquid crystal layer working as a microcavity have been studied using numerical simulation. It is demonstrated that the hybrid modes can be effectively tuned owing to the high sensitivity of the liquid crystal to the temperature and external electric field variations. It is established that the effect of temperature on the transmission spectrum of the investigated structure is most pronounced at the point of the phase transition of the liquid crystal to the iso…
We have developed a technique for realizing a two-dimensional quadrupolar microcavity with its deformation variable from 0% to 20% continuously. We employed a microjet ejected from a noncircular orifice in order to generate a stationary column with modulated quadrupolar deformation in its cross section. Wavelength red shifts of low-order cavity modes due to shape deformation were measured and were found to be in good agreement with the wave calculation for the same deformation, indicating the observed deformation is quadrupolar in nature.
We present an electrically switchable graphene terahertz (THz) modulator with a tunable-by-design optical bandwidth and we exploit it to compensate the cavity dispersion of a quantum cascade laser (QCL). Electrostatic gating is achieved by a metal-grating used as a gate electrode, with an HfO2/AlOx gate dielectric on top. This is patterned on a polyimide layer, which acts as a quarter wave resonance cavity, coupled with an Au reflector underneath. We get 90% modulation depth of the intensity, combined with a 20 kHz electrical bandwidth in the 1.9 _ 2.7 THz range. We then integrate our modulato…
Rapidly developing augmented reality (AR) and 3D holographic display technologies require spatial light modulators (SLM) with high resolution and viewing angle to be able to satisfy increasing customer demands. Currently available SLMs, as well as their performance, are limited by their large pixel sizes of the order of several micrometres. Further pixel size miniaturization has been stagnant due to the persistent challenge to reduce the inter-pixel crosstalk associated with the liquid crystal (LC) cell thickness, which has to be large enough to accumulate the required 2π phase difference. Her…
Spatial light modulators (SLMs) are the most relevant technology for dynamic wavefront manipulation. They find diverse applications ranging from novel displays to optical and quantum communications. Among commercial SLMs for phase modulation, Liquid Crystal on Silicon (LCoS) offers the smallest pixel size and, thus, the most precise phase mapping and largest field of view (FOV). Further pixel miniaturization, however, is not possible in these devices due to inter-pixel cross-talks, which follow from the high driving voltages needed to modulate the thick liquid crystal (LC) cells that are neces…
We report controllable manipulation of slow and fast light in a whispering-gallery-mode (WGM) microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fol…
An add-drop filter (ADF) fabricated using a whispering gallery mode resonator has different crosstalks for add and drop functions due to non-zero intrinsic losses of the resonator. Here, we show that introducing gain medium in the resonator and optically pumping it below the lasing threshold not only allows loss compensation to achieve similar and lower crosstalks but also tunability in bandwidth and add-drop efficiency. For an active ADF fabricated using an erbium-ytterbium co-doped microsphere, we achieved 24-fold enhancement in the intrinsic quality factor, 3.5-fold increase in drop efficie…
Switchable metamaterials offer unique solutions for efficiently manipulating electromagnetic waves, particularly for terahertz waves, which has been difficult since naturally occurring materials rarely respond to terahertz frequencies controllably. However, few terahertz modulators demonstrated to date exhibit simultaneously low attenuation and high modulation depth. In this letter we propose a new class of electrically-tunable terahertz metamaterial modulators employing metallic frequency-selective-surfaces (FSS) in conjunction with capacitively-tunable layers of electrons, promising near 100…
Optical microcavities are a powerful tool to enhance spontaneous emission of individual quantum emitters. However, the broad emission spectra encountered in the solid state at room temperature limit the influence of a cavity, and call for ultra-small mode volume. We demonstrate Purcell-enhanced single photon emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to a tunable fiber-based microcavity with a mode volume down to $1.0\,λ^{3}$. We record cavity-enhanced fluorescence images and study several single emitters with one cavity. The Purcell effect is evidenced by enhanced flu…
The spontaneous emission of atoms can be controlled by placing them between two mirrors that form an optical cavity. Rapid advances in material processing techniques in the last 10 years have made it possible to fabricate microscopic optical cavities that can be finely tuned into resonance with the emitter. This has enabled progress in single-photon sources, nano-lasers and spectroscopy of new nano-emitters such as semiconductor quantum dots and Nitrogen-vacancy centres in diamond. Here we introduce a step-by-step method for computing the Purcell factor of the latest generation of open tunable…
High efficiency and a compact footprint are desired properties for electro-optic modulators. In this paper, we propose, theoretically investigate and experimentally demonstrate a recirculating phase modulator, which increases the modulation efficiency by modulating the optical field several times in a non-resonant waveguide structure. The 'recycling' of light is achieved by looping the optical path that exits the phase modulator back and coupling it to a higher order waveguide mode, which then repeats its passage through the phase modulator. By looping the light back twice, we were able to dem…
Ultralow noise, yet tunable lasers are a revolutionary tool in precision spectroscopy, displacement measurements at the standard quantum limit, and the development of advanced optical atomic clocks. Further applications include LIDAR, coherent communications, frequency synthesis, and precision sensors of strain, motion, and temperature. While all applications benefit from lower frequency noise, many also require a laser that is robust and compact. Here, we introduce a dual-microcavity laser that leverages one chip-integrable silica microresonator to generate tunable 1550 nm laser light via sti…
Open-access microcavities are a powerful tool to enhance light-matter interactions for solid-state quantum and nano systems and are key to advance applications in quantum technologies. For this purpose, the cavities should simultaneously meet two conflicting requirements - full tunability to cope with spatial and spectral inhomogeneities of a material, and highest stability under operation in a cryogenic environment to maintain resonance conditions. To tackle this challenge, we have developed a fully-tunable, open-access, fiber-based Fabry-Pérot microcavity platform which can be operated also …
Electrically reconfigurable dipolar polaritons with highly tunable nonlinearity in a homobilayer microcavity
Tsinghua University（清华大学）；University of Washington（华盛顿大学）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；National Institute for Materials Science（国立材料研究所）；Nanyang Technological University（南洋理工大学）；Frontier Science Center for Quantum Information（量子信息前沿科学中心）
Dynamic color modulation in the composite structure of graphene microelectromechanical systems (MEMS)- photonic crystal microcavity is investigated in this work. The designed photonic crystal microcavity has three resonant standing wave modes corresponding to the three primary colors of red (R), green (G) and blue (B), forming strong localization of light in three modes at different positions of the microcavity. Once graphene is added, it can govern the transmittance of three modes. When graphene is located in the abdomen of the standing wave, which has strong light absorption and therefore th…
High-finesse, open-geometry microcavities have recently emerged as a versatile tool for enhancing interactions between photons and material systems, with a range of applications in quantum optics and quantum information science. However, mechanical vibrations pose a considerable challenge to their operation within a closed-cycle cryostat, particularly when spatial tunability and free-space optical access are required. Here, we present the design and characterization of a system that can achieve $\sim$16 pm-rms passive mechanical stability between two high-finesse mirrors while permitting both …
We study the mechanical stability of a tunable high-finesse microcavity under ambient conditions and investigate light-induced effects that can both suppress and excite mechanical fluctuations. As an enabling step, we demonstrate the ultra-precise electronic stabilization of a microcavity. We then show that photothermal mirror expansion can provide high-bandwidth feedback and improve cavity stability by almost two orders of magnitude. At high intracavity power, we observe self-oscillations of mechanical resonances of the cavity. We explain the observations by a dynamic photothermal instability…
Microcavities have long been recognized as indispensable elements in quantum photonic research due to their usefulness for enhanced light extraction and light-matter interaction. A conventional high-Q cavity structure typically allows only a single optical transition to be tuned into resonance with a specific mode. The transition to a more advanced double-cavity structure, however, introduces new and interesting possibilities such as enhancing two spectrally close optical transitions at the same time with two distinct cavity modes. Here, we investigate a cavity structure composed of a monolith…
We propose a mechanism of active near-field heat transfer modulation relying on externally tunable metamaterials. A large modulation effect is observed and can be explained by the coupling of surface modes, which is dramatically varied in the presence of controllable magnetoelectric coupling in metamaterials. We finally discuss how a practical picosecond-scale thermal modulator can be made. This modulator allows manipulating nanoscale heat flux in an ultrafast and noncontact (by optical means) manner.
Integrated lithium niobate (LN) photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties, low optical loss and excellent scalability. A key enabler for such systems is a highly linear electro-optic modulator that could faithfully covert analog electrical signals into optical signals. In this work, we demonstrate a monolithic integrated LN modulator with an ultrahigh spurious-free dynamic range (SFDR) of 120.04 dB Hz4/5 at 1 GHz, using a ring-assisted Mach-Zehnder interferometer configuration. The excellent synergy between …
Compact, lightweight and high-performance spatial light modulators (SLMs) are crucial for modern optical technologies. The drive for pixel miniaturization, necessary to improve their performance, has led to a promising alternative, active optical metasurfaces, which enable tunable subwavelength wavefront manipulation. Here, we demonstrate an all-solid-state programmable transmissive SLM device based on Huygens dielectric metasurfaces. The metasurface features electrical tunability, provided by mature liquid crystals (LCs) technology. In contrast to conventional LC SLMs, our device enables high…
Random lasers with low spatial coherence have important potential applications in high quality imaging and displaying. Here, a random laser with tunable angular spectra is proposed and fabricated through directly coupling an asymmetric microcavity with a commercial optical fiber. The designed random laser demonstrates pumping direction-independence property in working threshold, and good storage stability.More importantly, the angular spectrum can be adjusted by pumping different microcavities on the fiber, the output random lasing with ring-shape in momentum space are used as illumination sou…
Light responsive devices employing molecular photo-switches are interesting for displays and dynamic light filtering. In this work, polymeric microcavities embedding a layer of photochromic compound have been studied by means of the transfer matrix method. Different polymers, such as poly vinyl carbazole, poly styrene and cellulose acetate, have been used. A microcavity that includes random one-dimensional photonic structures sandwiching the photochromic layer has also been studied. Propagation of light pulses through the microcavities has been analysed.
Densely integrated active photonics is key for next generation on-chip networks for addressing both footprint and energy budget concerns. However, the weak light-matter interaction in traditional active Silicon optoelectronics mandates rather sizable device lengths. The ideal active material choice should avail high index modulation while being easily integrated into Silicon photonics platforms. Indium tin oxide (ITO) offers such functionalities and has shown promising modulation capacity recently. Interestingly, the nanometer-thin unity-strong index modulation of ITO synergistically combines …
We demonstrate a collinear acousto-optic modulator in a suspended film of lithium niobate employing a high-confinement, wavelength-scale waveguide. By strongly confining the optical and mechanical waves, this modulator improves by orders of magnitude a figure-of-merit that accounts for both acousto-optic and electro-mechanical efficiency. Our device demonstration marks a significant technological advance in acousto-optics that promises a novel class of compact and low-power frequency shifters, tunable filters, non-magnetic isolators, and beam deflectors.
We have demonstrated a frequency-stabilized tunable 318.6 nm ultraviolet (UV) laser system for the single-photon 6S1/2 - nP (n = 70 ~ 100) Rydberg excitation of cesium atoms. The 637.2 nm laser produced by single-pass sum frequency generation from two infrared fiber lasers is offset locked to a high-finesse ultra-low expansion (ULE) optical cavity placed in ultra-high vacuum using the electronic sideband locking technique. The generated 318.6 nm UV laser via cavity-enhanced second-harmonic generation can be continuously tuned over 4 GHz by indirectly changing modulation frequency on the electr…
Fano resonance is widely discussed in designing novel terahertz components, such as sensors, filters, modulators, and group delay modules. Usually, high quality (Q) factor and flexible tunability of Fano resonance are key requirements for these applications. Here, we present tunable terahertz Fano resonance with a Q factor of 2095 at 0.439 THz in coupled terahertz whispering-gallery-mode resonators (WGMRs). Coupling between a relatively low Q (578) quartz ring and a high Q (2095) silicon ring is employed to generate the Fano resonance. The resonant frequency of the Fano resonance can be active…
An electro-absorption optical modulator concept based upon a dual-graphene layer is presented. The device consists of a silicon-on-insulator waveguide upon which two graphene layers reside, separated by a thin insulating region. The lower graphene acts as a tunable absorber, while the upper layer functions as a transparent gate electrode. Calculations based upon realistic graphene material properties show that 3-dB bandwidths over 100 GHz (30 GHz) are possible at near- (λ=1.55 μm) and mid- (λ=3.5μm) infrared bands. The effect of background doping and potential fluctuations on the bandwidth, mo…
Open Fabry-Perot microcavities represent a promising route for achieving a quantum electrodynamics (cavity-QED) platform with diamond-based emitters. In particular, they offer the opportunity to introduce high purity, minimally fabricated material into a tunable, high quality factor optical resonator. Here, we demonstrate a fiber-based microcavity incorporating a thick (> 10 μm) diamond membrane with a finesse of 17,000, corresponding to a quality factor Q ~ $10^6$. Such minimally fabricated, thick samples can contain optically stable emitters similar to those found in bulk diamond. We observe…
Controlling light polarization is one of the most essential routines in modern optical technology. Since the demonstration of optical pulse shaping by spatial light modulators and its potential in controlling the quantum reaction pathways, it paved the way for many applications as a coherent control of the photoionization process or as polarization shaping of terahertz (THz) pulses. Here, we evidenced efficient nonresonant and noncollinear $χ^{(2)}$-type light-matter interaction in femtosecond polarization-sensitive time-resolved optical measurements. Such nonlinear optical interaction of visi…
Typical microresonators exhibit a large frequency spacing between resonances and a limited tunability. This impedes their use in a large class of applications which require a resonance of the microcavity to coincide with a predetermined frequency. Here, we experimentally overcome this limitation with highly prolate-shaped whispering-gallery-mode "bottle microresonators" fabricated from standard optical glass fibers. Our resonators combine an ultra-high quality factor of 360 million, a small mode volume, and near lossless fibre coupling, characteristic of whispering-gallery-mode resonators, wit…
The field of spinoptronics is underpinned by good control over photonic spin-orbit coupling in devices that possess strong optical nonlinearities. Such devices might hold the key to a new era of optoelectronics where momentum and polarization degrees-of-freedom of light are interwoven and interfaced with electronics. However, manipulating photons through electrical means is a daunting task given their charge neutrality and requires complex electro-optic modulation of their medium. In this work, we present electrically tunable microcavity exciton-polariton resonances in a Rashba-Dresselhaus spi…
We report controlled manipulation of mode splitting in an optical microresonator coupled to two nanoprobes. It is demonstrated that, by controlling the positions of the nanoprobes, the split modes can be tuned simultaneously or individually and experience crossing or anti-crossing in frequency and linewidth. A tunable transition between standing wave mode and travelling wave mode is also observed. Underlying physics is discussed by developing a two-scatterer model which can be extended to multiple scatterers. Observed rich dynamics and tunability of split modes in a single microresonator will …
Optical modulators are essential parts of photonic circuits to encode electro-optical signals to the optical domain. Here, using arrays of multipixel toroidal plasmonic terahertz (THz) metamolecules, we developed a plasmonic metamodulator with high efficiency and tunability. Using the ultrasensitivity of the excited toroidal momentum to the incident THz beam power, we numerically and experimentally studied the plasmonic response of the proposed device. We showed that the proposed THz toroidal metamodulator have strong potential to be employed for practical advanced communication applications.
In order to overcome the challenge of obtaining high modulation depth due to weak graphene-light interaction, a graphene-on-silicon nitride (SiNx) microring resonator based on graphene's gate-tunable optical conductivity is proposed and studied. Geometrical parameters of graphene-on-SiNx waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB/μm and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40-μm-radius microring resonator, where electro-absorptive and electro-refractive modulation are both taken into a…
Tunable optical material properties enable novel applications in both versatile metamaterials and photonic components including optical sources and modulators. Transparent conductive oxides (TCOs) are able to highly tune their optical properties with applied bias via altering their free carrier concentration and hence plasma dispersion. The TCO material indium tin oxide (ITO) exhibits unity-strong index changes, and epsilon-near-zero behavior. However, with such tuning the corresponding high optical losses, originating from the fundamental Kramers-Kronig relations, result in low cavity finesse…
All-dielectric optical metasurfaces can locally control the amplitude and phase of light at the nanoscale, enabling arbitrary wavefront shaping. However, lack of post-fabrication tunability has limited the true potential of metasurfaces for many applications. Here, we utilize a thin liquid crystal (LC) layer as a tunable medium surrounding the metasurface to achieve a phase-only spatial light modulator (SLM) with high reflection in the visible frequency, exhibiting an active and continuous resonance tuning with associated 2pi phase control and uncoupled amplitude. Dynamic wavefront shaping is …
Hybrid light-matter states, polaritons, are one of the central concepts in modern quantum optics and condensed matter physics. Polaritons emerge as a result of strong interaction between an optical mode and a material resonance, which is frequently realized in molecular, van der Waals, or solid-state platforms (1-7). However, this route requires accurate (nano)fabrication and often lacks simple means for tunability, which could be disadvantageous in some applications. Here, we use a different approach to realize polaritonic states by employing a stable equilibrium between two parallel gold nan…
Optical implementation of artificial neural networks has been attracting great attention due to its potential in parallel computation at speed of light. Although all-optical deep neural networks (AODNNs) with a few neurons have been experimentally demonstrated with acceptable errors recently, the feasibility of large scale AODNNs remains unknown because error might accumulate inevitably with increasing number of neurons and connections. Here, we demonstrate a scalable AODNN with programmable linear operations and tunable nonlinear activation functions. We verify its scalability by measuring an…
