Wavelength-dependent polarization state of light carries crucial information about light-matter interactions. However, its measurement is limited to bulky, energy-consuming devices, which prohibits many modern, portable applications. Here, we propose and demonstrate a chip-scale spectropolarimeter implemented using a CMOS-compatible silicon photonics technology. Four compact Vernier microresonator spectrometers are monolithically integrated with a broadband polarimeter consisting of a 2D nanophotonic antenna and a polarimetric circuit to achieve full-Stokes spectropolarimetric analysis. The proposed device offers a solid-state spectropolarimetry solution with a small footprint of 1*0.6 mm2 and low power consumption of 360 mW}. Full-Stokes spectral detection across a broad spectral range of 50 nm with a resolution of 1~nm is demonstrated in characterizing a material possessing structural chirality. The proposed device may enable a broader application of spectropolarimetry in the fields ranging from biomedical diagnostics and chemical analysis to observational astronomy.
Metasurfaces enable exceptional control over the light with surface-confined planar components, offering the fascinating possibility of very dense integration and miniaturization in photonics. Here, we design, fabricate and experimentally demonstrate chip-size plasmonic spectropolarimeters for simultaneous polarization state and wavelength determination. Spectropolarimeters, consisting of three gap-plasmon phase-gradient metasurfaces that occupy 120° circular sectors each, diffract normally incident light to six predesigned directions, whose azimuthal angles are proportional to the light wavel…
Using a compact optically-pumped silicon nanophotonic chip consisting of coupled silicon microrings, we generate photon pairs in multiple pairs of wavelengths around 1.55 μm. The wavelengths are tunable over several nanometers, demonstrating the capability to generate wavelength division multiplexed photon pairs at freely-chosen telecommunications-band wavelengths.
Silicon quantum photonics provides a promising pathway to realize large-scale quantum photonic integrated circuits (QPICs) by exploiting the power of complementary-metal-oxide-semiconductor (CMOS) technology. Toward scalable operation of such silicon-based QPICs, a straightforward approach is to integrate deterministic single-photon sources (SPSs). To this end, hybrid integration of deterministic solid-state SPSs, such as those based on InAs/GaAs quantum dots (QDs), is highly promising. However, the spectral and spatial randomness inherent in the QDs pose a serious challenge for scalable imple…
We demonstrate the generation and demultiplexing of quantum correlated photons on a monolithic photonic chip composed of silicon and silica-based waveguides. Photon pairs generated in a nonlinear silicon waveguide are successfully separated into two optical channels of an arrayed-waveguide grating fabricated on a silica-based waveguide platform.
Here we demonstrate quantum interference of photons on a Silicon chip produced from a single ring resonator photon source. The source is seamlessly integrated with a Mach-Zehnder interferometer, which path entangles degenerate bi-photons produced via spontaneous four wave mixing in the Silicon ring resonator. The resulting bi-photon N00N state is controlled by varying the relative phase of the integrated Mach-Zehnder interferometer, resulting in high two-photon interference visibilities of V~96%. Furthermore, we show that the interference can be produced using pump wavelengths tuned to all of …
Integrated optical devices may replace bulk crystal or fiber based assemblies with a more compact and controllable photon pair and heralded single photon source and generate quantum light at telecommunications wavelengths. Here, we propose that a periodic waveguide consisting of a sequence of optical resonators may outperform conventional waveguides or single resonators and generate more than 1 Giga-pairs per second from a sub-millimeter-long room-temperature silicon device, pumped with only about 10 milliwatts of optical power. Furthermore, the spectral properties of such devices provide nove…
Integrated quantum photonics relies critically on the purity, scalability, integrability, and flexibility of a photon source to support diverse quantum functionalities on a single chip. Up to date, it remains an open challenge to realize an efficient monolithic photon-pair source for on-chip application. Here we report a device on the silicon-on-insulator platform that utilizes dramatic cavity enhanced four-wave mixing in a high-Q silicon microdisk resonator. The device is able to produce high-purity photon pairs in a comb fashion, with an unprecedented spectral brightness of $6.24 \times 10^7…
With high integration density and excellent optical properties, silicon photonics is becoming a promising platform for complete integration and large-scale optical quantum information processing. Scalable quantum information applications need photon generation and detection to be integrated on the same chip, and we have seen that various devices on the silicon photonic chip have been developed for this goal. This paper reviews the relevant research results and state-of-the-art technologies on the silicon photonic chip for scalable quantum applications. Despite the shortcomings, properties of s…
We demonstrate continuous tuning of the squeezing level generated in a double-ring optical parametric oscillator by externally controlling the coupling condition using electrically controlled integrated microheaters. We accomplish this by utilizing the avoided crossing exhibited by a pair of coupled silicon nitride microring resonators. We directly detect a change in the squeezing level from 0.5 dB in the undercoupled regime to 2 dB in the overcoupled regime, which corresponds to a change in the generated on-chip squeezing factor from 0.9 dB to 3.9 dB. Such wide tunability in the squeezing lev…
Integrated Silicon photonics has played an important role in advancing the applications of quantum information and quantum science. However, due to different material properties, it is challenging to integrate all components with excellent performance based on homogeneous material. Here, by combining high nonlinearity and low losses in a heterogeneous silicon platform, we efficiently generate high-quality photon pairs through spontaneous four-wave mixing in hydrogenated amorphous silicon waveguide and route them off-chip through low loss silicon nitride waveguide. A record high coincidence- to…
Integrated photonic circuits are one of the most promising platforms for large-scale photonic quantum information systems due to their small physical size and stable interferometers with near-perfect lateral-mode overlaps. Since many quantum information protocols are based on qubits defined by the polarization of photons, we must develop integrated building blocks to generate, manipulate, and measure the polarization-encoded quantum state on a chip. The generation unit is particularly important. Here we show the first integrated polarization-entangled photon pair source on a chip. We have impl…
We present the design, fabrication and characterization of high quality factor silicon nitride nanobeam PhC cavities at visible wavelengths for coupling to diamond color centers in a cavity QED system. We demonstrate devices with a quality factor of about 24;000 around the zero-phonon line of the germanium-vacancy center in diamond. We also present an efficient fiber-to-waveguide coupling platform for suspended nanophotonics. By gently changing the corresponding effective indices at the fiber-waveguide interface, we achieve an efficiency of about 96% at the cavity resonance.
We present a scheme for on-chip optical transduction of strain and displacement of Graphene-based Nano-Electro-Mechanical Systems (NEMS). A detailed numerical study on the feasibility of three silicon-photonic integrated circuit configurations is presented: Mach-Zehnder Interferometer(MZI), micro-ring resonator and ring-loaded MZI. An index-sensing based technique using a Mach-Zehnder Interferometer loaded with a ring resonator with a moderate Q-factor of 2400 can yield a sensitivity of 28 fm/sqrt(Hz), and 6.5E-6 %/sqrt(Hz) for displacement and strain respectively. Though any phase sensitive i…
Implementing large instances of quantum algorithms requires the processing of many quantum information carriers in a hardware platform that supports the integration of different components. While established semiconductor fabrication processes can integrate many photonic components, the generation and algorithmic processing of many photons has been a bottleneck in integrated photonics. Here we report the on-chip generation and processing of quantum states of light with up to eight photons in quantum sampling algorithms. Switching between different optical pumping regimes, we implement the Scat…
Quantum photonic integrated circuit (QPIC) is a promising tool for constructing integrated devices for quantum technology applications. In the optical regime, silicon photonics empowered by complementary-metal-oxide-semiconductor (CMOS) technology provides optical components useful for realizing large-scale QPICs. Optical nonlinearity at the single-photon level is required for QPIC to facilitate photon-photon interaction. However, to date, realization of optical elements with deterministic( i.e., not probabilistic) single-photon nonlinearity by using silicon-based components is challenging, de…
Quantum information processing holds great promise for communicating and computing data efficiently. However, scaling current photonic implementation approaches to larger system size remains an outstanding challenge for realizing disruptive quantum technology. Two main ingredients of quantum information processors are quantum interference and single-photon detectors. Here we develop a hybrid superconducting-photonic circuit system to show how these elements can be combined in a scalable fashion on a silicon chip. We demonstrate the suitability of this approach for integrated quantum optics by …
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…
Time-correlated photon pairs are generated by triply-resonant Four-Wave-Mixing in a In$_{0.5}$Ga$_{0.5}$P Photonic Crystal cavitiy. Maximal efficiency is reached by actively compensating the residual spectral misalignment of the cavity modes. The generation rate reaches 5 MHz in cavities with Q-factor $\approx 4\times 10^4$, more than one order of magnitude larger than what is measured using ring resonators with similar Q factors fabricated on the same chip. The Photonic Crystal source is integrated on a Si photonic circuit, an important asset for applications in quantum technologies.
In this paper, we present refractive index measurement using a double-slot silicon waveguide-based Mach Zehnder interferometer. We present a double-slot waveguide that offers the best sensitivity and limit of detection compared to wire and single-slot waveguides. We demonstrate ultra-low loss coupling between a single-mode waveguide and a double-slot waveguide and experimental proof for double-slot excitation. The double-slot waveguide is used to demonstrate a highly sensitive concentration sensor. An unbalanced Mach-Zehnder is used as the sensor device to demonstrate concentrations of Potassi…
Entanglement is a counterintuitive feature of quantum physics that is at the heart of quantum technology. High-dimensional quantum states offer unique advantages in various quantum information tasks. Integrated photonic chips have recently emerged as a leading platform for the generation, manipulation and detection of entangled photons. Here, we report a silicon photonic chip that uses novel interferometric resonance-enhanced photon-pair sources, spectral demultiplexers and high-dimensional reconfigurable circuitries to generate, manipulate and analyse path-entangled three-dimensional qutrit s…
We report on the fabrication and characterization of photonic-based nanothermometers, a silicon photonic Bragg grating and photonic crystal cavity. When cladded with silicon dioxide layer the sensors have at least eight times better sensitivity compared to the sensitivity of conventional fiber Bragg grating sensors. We demonstrate that these photonic thermometers are a viable temperature sensing solution.
Modifying light fields at single-photon level is a key challenge for upcoming quantum technologies and can be realized in a scalable manner through integrated quantum photonics. Laser-written diamond photonics offers three-dimensional fabrication capabilities and large mode-field diameters matched to fiber optic technology, though limiting the cooperativity at the single-emitter level. To realize large cooperativities, we combine excitation of single shallow-implanted silicon vacancy centers via large numerical aperture optics with detection assisted by laser-written type-II waveguides. We dem…
Optical isolation is a long pursued object with fundamental difficulty in integrated photonics. As a step towards this goal, we demonstrate the design, fabrication, and characterization of on-chip wavelength-scale optical diodes that are made from the heterojunction between two different silicon two-dimensional square-lattice photonic crystal slabs with directional bandgap mismatch and different mode transitions. The measured transmission spectra show considerable unidirectional transmission behavior, in good agreement with numerical simulations. The experimental realization of on-chip optical…
We demonstrate fully crystalline, single-mode ultrahigh quality factor integrated microresonators comprising epitaxially grown Si$_{0.86}$Ge$_{0.14}$ waveguide cores with silicon claddings. These waveguides support resonances with internal $Q >10^8$ for both polarization modes, a nearly order-of-magnitude improvement over that seen in prior integrated Si photonics platforms. The maximum $Q$ is $1.71\pm0.06 \times 10^8$ for the transverse magnetic (TM) polarization mode, corresponding to a loss of $0.39\pm0.02$ dB/m. Together with silicon's strong Kerr nonlinearity and low losses in the optical…
Micron scale silicon nitride (SiN_x) microdisk optical resonators are demonstrated with Q = 3.6 x 10^6 and an effective mode volume of 15 (λ/ n)^3 at near visible wavelengths. A hydrofluoric acid wet etch provides sensitive tuning of the microdisk resonances, and robust mounting of a fiber taper provides efficient fiber optic coupling to the microdisks while allowing unfettered optical access for laser cooling and trapping of atoms. Measurements indicate that cesium adsorption on the SiN_x surfaces significantly red-detunes the microdisk resonances. A technique for parallel integration of mult…
Advances in quantum photonics have shown that chip-scale quantum devices are translating from the realm of basic research to applied technologies. Recent developments in integrated photonic circuits and single photon detectors indicate that the bottleneck for fidelity in quantum photonic processes will ultimately lie with the photon sources. We present and demonstrate a silicon nanophotonic chip capable of emitting telecommunication band photon pairs that exhibit the highest raw degree of time-energy entanglement from a micro/nanoscale source, to date. Biphotons are generated through cavity-en…
Aluminum nitride (AlN) is an emerging material for integrated quantum photonics due to its large $χ^{(2)}$ nonlinearity. Here we demonstrate the hybrid integration of AlN on silicon nitride (SiN) photonic chips. Composite microrings are fabricated by reactive DC sputtering of c-axis oriented AlN on top of pre-patterned SiN. This new approach does not require any patterning of AlN and depends only on reliable SiN nanofabrication. This simplifies the nanofabrication process drastically. Optical characteristics, such as the quality factor, propagation losses and group index, are obtained. Our hyb…
We demonstrate the possibility of trapping about one hundred million rubidium atoms in a magneto-optical trap with several of the beams passing through a transparent atom chip mounted on a vacuum cell wall. The chip is made of a gold microcircuit deposited on a silicon carbide substrate, with favorable thermal conductivity. We show how a retro-reflected configuration can efficiently address the chip birefringence issues, allowing atom trapping at arbitrary distances from the chip. We also demonstrate detection through the chip, granting a large numerical aperture. This configuration is compare…
Integrated entangled photon-pair sources are key elements for enabling large-scale quantum photonic solutions, and addresses the challenges of both scaling-up and stability. Here we report the first demonstration of an energy-time entangled photon-pair source based on spontaneous parametric down-conversion in silicon-based platform through an optically induced second-order ($χ^{(2)}$) nonlinearity, ensuring type-0 quasi-phase-matching of fundamental harmonic and its second-harmonic inside the waveguide. The developed source shows a coincidence-to-accidental ratio of 1635 at 8 of $μ$W pump powe…
We demonstrate the efficient coupling (99.5%) of a silica whispering gallery mode microresonator directly with a silicon chip by using a silicon photonic crystal waveguide as a coupler. The efficient coupling is attributed to the small effective refractive index difference between the two devices. The large group index of the photonic crystal waveguide mode also contributes to the efficient coupling. A coupling Q of 2.68*10^6 is obtained, which allows us to achieve the critical coupling of a silica whispering gallery mode with an intrinsic Q of close to 10^7 with a Si chip.
High-dimensional entanglement is significant for the fundamental studies of quantum physics and offers unique advantages in various quantum information processing (QIP) tasks. Integrated quantum devices have recently emerged as a promising platform for creating, processing, and detecting complex high-dimensional entangled states. A crucial step towards practical quantum technologies is to verify that these devices work reliably with an optimal strategy. In this work, we experimentally implement an optimal quantum verification strategy on a three-dimensional maximally entangled state using loca…
We demonstrate heralded single photon generation in a CMOS-compatible silicon nanophotonic device. The strong modal confinement and slow group velocity provided by a coupled resonator optical waveguide (CROW) produced a large four-wave-mixing nonlinearity coefficient gamma_eff ~4100 W^-1 m^-1 at telecommunications wavelengths. Spontaneous four-wave-mixing using a degenerate pump beam at 1549.6 nm created photon pairs at 1529.5 nm and 1570.5 nm with a coincidence-to-accidental ratio exceeding 20. A photon correlation measurement of the signal (1529.5 nm) photons heralded by the detection of the…
We present a plasmonic modulator based on hybrid orthogonal silver junctions using vanadium dioxide as the modulating material on the silicon on insulator. The modulator has an ultra-compact footprint of 1.8μm x 1μm with a 100nm x 100nm modulating section based on the orthogonal geometry. We take advantage of large change in the refractive index of vanadium dioxide during its phase transition to achieve a high modulation depth of 46.89dB/μm. We also provide a fabrication strategy for the development of this device. The device geometry has potential applications in the development of next gener…
All-optical integrated circuits for computing and information processing have been pursued for decades as a potential strategy to overcome the speed limitations intrinsic to electronics. However feasible on-chip integrated logic units and devices still have been limited by its size, quality, scalability, and reliability. Here we demonstrate all-passive on-chip optical AND and NAND logic gates made from a directional emitting cavity connecting two ultrasmall photonic crystal heterojunction diodes. The measured transmission spectra show more than 10dB contrast of the logic transport with a high …
The exponential growth of photonic quantum technologies is driving the demand of tools for measuring the quality of their information carriers. One of the most prominent is Stimulated Emission Tomography (SET), which uses classical coherent fields to measure the Joint Spectral Amplitude (JSA) of photon pairs with high speed and resolution. While the modulus of the JSA can be directly addressed from a single intensity measurement, the retrieval of the Joint Spectral Phase (JSP) is far more challenging and received minor attentions. However, a wide class of spontaneous sources of technological r…
Silicon-on-chip (SOI) photonic circuit is the most promising platform for scalable quantum information technology for its low loss, small footprint, CMOS-compatible and telecom communications techniques compatible. Multiple multiplexed entanglement sources include: energy-time, time-bin and polarization entangled sources based on 1-cm length single silicon nanowire, all these sources are compatible with (100GHz) dense-wave-division-multiplexing (DWDM) system. Different methods such as two photon interference pattern, Bell-Inequality and quantum state tomography are used to characterize the qua…
Silicon photonics enables wafer-scale integration of optical functionalities on chip. A silicon-based laser frequency combs could significantly expand the applications of silicon photonics, by providing integrated sources of mutually coherent laser lines for terabit-per-second transceivers, parallel coherent LiDAR, or photonics-assisted signal processing. Here, we report on heterogeneously integrated laser soliton microcombs combining both InP/Si semiconductor lasers and ultralow-loss silicon nitride microresonators on monolithic silicon substrate. Thousands of devices are produced from a sing…
We demonstrate a silicon-chip biphoton source with an unprecedented quantum cross correlation up to ${\rm g_{si}^{(2)}(0) = (2.58 \pm 0.16) \times 10^4}$. The emitted biphotons are intrinsically single-mode, with self correlations of ${\rm g_{ss}^{(2)}(0) = 1.90 \pm 0.05}$ and ${\rm g_{ii}^{(2)}(0) = 1.87 \pm 0.06}$ for signal and idler photons, respectively. We observe the waveform asymmetry of cross correlation between signal and idler photons and reveal the identical and non-exponential nature of self correlations of individual signal and idler photon modes, which is a nature of cavity-enha…
As an important degree of freedom (DoF) in integrated photonic circuits, the orthogonal transverse mode provides a promising and flexible way to increasing communication capability, for both classical and quantum information processing. To construct large-scale on-chip multimode multi-DoF quantum systems, a transverse mode-encoded controlled-NOT (CNOT) gate is necessary. Here, through design and integrate transverse mode-dependent directional coupler and attenuators on a silicon photonic chip, we demonstrate the first multimode implementation of a two-qubit quantum gate. With the aid of state …
We demonstrate an external cavity laser formed by combining a silicon nitride photonic integrated circuit with a reflective semiconductor optical amplifier. The laser uses an alignment tolerant edge coupler formed by a multi-mode waveguide splitter right at the edge of the silicon nitride chip that relaxes the required alignment to the III-V gain chip and equally splits the power among its two output waveguides. Both the ground and first order mode are excited in the coupler and reach the quadrature condition at the waveguide junction, ensuring equal power to be coupled to both. Two high-quali…
We present the first study of parametric amplification in hydrogenated amorphous silicon waveguides. Broadband on/off amplification up to 26.5~dB at telecom wavelength is reported. Measured nonlinear parameter is 770~$\textrm{W}^{-1} \textrm{m}^{-1}$, nonlinear absorption 28~$\textrm{W}^{-1} \textrm{m}^{-1}$, bandgap $1.61$~eV.
Squeezed states are a primary resource for continuous-variable (CV) quantum information processing. To implement CV protocols in a scalable and robust way, it is desirable to generate and manipulate squeezed states using an integrated photonics platform. In this Letter, we demonstrate the generation of quadrature-phase squeezed states in the radio-frequency carrier sideband using a small-footprint silicon-nitride microresonator with a dual-pumped four-wave-mixing process. We record a squeezed noise level of 1.34 dB ($\pm$0.16 dB) below the photocurrent shot noise, which corresponds to 3.09 dB …
Hybrid SiN-QD microlasers coupled to a passive SiN output waveguide with 7μm diameter and record low threshold density of 27 μJ cm-2 are demonstrated. A new design and unique processing scheme starting from SiN/QD/SiN stacks offer long term stability and facilitate in depth laser characterization. This approach opens up new paths for optical communication, lab-on-a-chip, gas sensing and, potentially, on-chip cavity quantum electrodynamics and quantum optics.
Instantaneous frequency measurement (IFM) of microwave signals is a fundamental functionality for applications ranging from electronic warfare to biomedical technology. Photonic techniques, and nonlinear optical interactions in particular, have the potential to broaden the frequency measurement range beyond the limits of electronic IFM systems. The key lies in efficiently harnessing optical mixing in an integrated nonlinear platform, with low losses. In this work, we exploit the low loss of a 35 cm long, thick silicon waveguide, to efficiently harness Kerr nonlinearity, and demonstrate the fir…
2.5D chiplet systems have been proposed to improve the low manufacturing yield of large-scale chips. However, connecting the chiplets through an electronic interposer imposes a high traffic load on the interposer network. Silicon photonics technology has shown great promise towards handling a high volume of traffic with low latency in intra-chip network-on-chip (NoC) fabrics. Although recent advances in silicon photonic devices have extended photonic NoCs to enable high bandwidth communication in 2.5D chiplet systems, such interposer-based photonic networks still suffer from high power consump…
Silicon is an excellent material for microelectronics and integrated photonics with untapped potential for mid-IR optics. Despite broad recognition of the importance of the third dimension, current lithography methods do not allow fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Embedded optical elements, like in glass, electronic devices and better electronic-photonic integration are lacking. Here, we demonstrate laser-based fabrication of complex 3…
We report an efficient energy-time entangled photon-pair source based on four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks to suitable optimization, the source shows a large spectral brightness of 400\,pairs of entangled photons /s/MHz for $\rm 500\,μW$ pump power. Additionally, the resonator has been engineered so as to generate a frequency comb structure compatible with standard telecom dense wavelength division multiplexers. We demonstrate high-purity energy-time entanglement, i.e., free of photonic noise, with near perfect raw visibilities ($>$~98\%) between va…
