Photonic Channel Research Articles

Wide-band RF receiver based on dual-OFC-based photonic channelization and spectrum stitching technique.

A novel wide-band RF receiver based on a dual-OFC-based channelization and spectrum stitching technique is proposed and demonstrated experimentally. In the scheme, a dual-OFC-based channelizer is utilized as the front-end to slice the RF signals into multiple channels. In the back-end, through the channel estimation and spectrum stitching, the received signals can be well reconstructed in the digital domain. A proof-of-concept experiment is performed, in which signals with 3 GHz bandwidths are sliced and reconstructed using the proposed receiver with a normalized mean squared error (NMSE) of 7.9×10-3. The performances of the reconstructed signals on pulse compression are also demonstrated to evaluate the potential of the proposed technique in practical applications.

Loss-Less Elliptical Channel Drop Filter for WDM Applications

Abstract In this paper, we proposed optical filter based on two-dimensional photonic crystal elliptical channel for wavelength division multiplexing. We employed ring resonator with ellipse shaped core in proposed structure. The resonance wavelength of the ring resonators depends on two parameters: refractive index and radius of dielectric rods. We investigate the physical parameters governing the filter performance. Our results show that the transmission efficiency is 100 % due to nearly zero reflection and loss in channel. Band width of 4 nm and quality factor of 389 is obtained for filter. Also, the total footprint of proposed structure is 230.4 µm2 which makes it suitable for all optical integrated circuits.

High purity single photons entangled with an atomic qubit.

Trapped atomic ions are an ideal candidate for quantum network nodes, with long-lived identical qubit memories that can be locally entangled through their Coulomb interaction and remotely entangled through photonic channels. The integrity of this photonic interface is generally reliant on the purity of single photons produced by the quantum memory. Here, we demonstrate a single-photon source for quantum networking based on a trapped 138Ba+ ion with a single photon purity of g (2)(0)=(8.1±2.3)×10-5 without background subtraction. We further optimize the tradeoff between the photonic generation rate and the memory-photon entanglement fidelity for the case of polarization photonic qubits by tailoring the spatial mode of the collected light.

Probing the charm-Higgs–Yukawa coupling via Higgs boson decay to hc plus a photon

In this paper, we investigate the decay of the Higgs boson to hc plus a photon in the non-relativistic quantum chromodynamics (QCD) theoretical framework. Compared with the Higgs decay to J/ψ plus a photon channel, this process makes a indirect contribution, and can be used to detect the Yukawa coupling of Higgs and charm quarks. The results show that the decay branch ratio of this process is about 10−8. If we take into account the 10−3 efficiency in the hc detection, no events will be available even in the case of 30 ab−1 luminosity at FCC-pp with a 100 TeV center of mass energy. However, if the detection efficiency of hc is greatly improved in the future, this process will play an important role in linear e+ e− future colliders and at LHCb. Moreover, this process should also play an important role when the anomalous charm–Yukawa couplings are larger and direct sensitivity.

Switchable slow light rainbow trapping and releasing in strongly coupling topological photonic systems

We design and present a switchable slow light rainbow trapping (SLRT) state in a strongly coupling topological photonic system made from a magneto-optical photonic crystal waveguide channel. The waveguide channel supports slow light states with extremely small group velocity (vg=2.1×10−6c), low group-velocity dispersion, and a broadband operation bandwidth (3.60–4.48 GHz, near 22% of bandwidth). These slow light states originate from the strong coupling between two counter propagating topological photonic states. Under a gradient magnetic field, different frequency components of a wave packet are separated and stored at different positions for a long temporal duration with high spatial precision (without crosstalk and overlap between the electric fields of different frequencies) to form SLRT. Besides, these SLRT states can be easily switched among the forbidden state, trapped state, and releasing state by tuning the external magnetic field. The results suggest that the topological photonic state can offer a precise route of spatial-temporal-spectral control upon a light signal and find applications for optical buffers, broadband slow light systems, optical filters, wavelength-division multiplexing, and other optical communication devices.

Compact photonic crystal multichannel drop filter for CWDM systems

A novel photonic crystal channel drop filter (PCCDF) is proposed to drop four coarse wavelength division multiplexing (CWDM) channels at 1490 nm, 1510 nm, 1530 nm and 1550 nm. A special coupled dual-loop design was used for multichannel forward/backward dropping for the first time. Due to the reduced number of the dropping resonators with this design, the proposed multichannel PCCDF has a very compact size (338 μ m2). High transmission efficiencies at the four ITU wavelengths (87.87%, 93.99%, 85.40% and 84.24%) can be obtained simultaneously. Furthermore, the same dimension parameters (lattice constant and rod radius) of the dual-loop resonators are helpful for easy fabrication. The proposed device could be used in future photonic integrated circuit-based CWDM communication systems.

Direct Determination of Redox Statuses in Biological Thiols and Disulfides with Noncovalent Interactions of Poly(ionic liquid)s.

The three most important redox couples, including cysteine (Cys)/cystine (Cyss), homocysteine (Hcys)/homocystine (Hcyss), and reduced glutathione (GSH)/glutathione disulfide (GSSG), are closely associated with human aging and many diseases. Thus, it is highly important to determine their redox statuses at the following two levels: (i) the redox identity in different thiols/disulfides and (ii) the redox ratio in a mixture of a specific couple. Herein, by using one single AIE-doped (AIE, aggregation-induced emission) photonic-structured poly(ionic liquid) (PIL) sphere as a virtual sensor array, we realize a direct determination of the redox status without a reducing pretreatment of disulfides, which will greatly promote the development of high-throughput and simple procedures. The pattern-recognition method uses the multiple noncovalent interactions of imidazolium-based PILs with these redox species to produce differential responses in both the photonic crystal and fluorescence dual channels. On the one hand, a single sphere enables the direct and simultaneous discrimination of the redox identities of Cys, Cyss, Hcys, Hcyss, GSH, and GSSG under the interference of other five commonly occurring thiols. On the other hand, this sphere also allows for not only a direct quantification of the GSH/GSSG ratios without previously determining the individual concentrations of GSH and GSSG but also the accurate prediction of the ratios in unknown redox samples. To further demonstrate applications of this method, redox mixtures in a biological sample are differentiated. Additionally, quantum calculations further support our assignments for interactions between the imidazolium-based PILs and these redox species.

High-visibility Franson interference of time-energy entangled photon pairs from warm atomic ensemble.

We experimentally demonstrate Franson interference of a time-energy entangled photon pair generated via collective two-photon coherence in the 5S1/2-5P3/2-5D5/2 transition of warm Rb87 atoms. The two unbalanced Michelson interferometers used in our setup are spatially separated in order to understand entanglement as a nonlocal property of the photon pairs from the warm atomic ensemble. We observe a Franson interference fringe with a high visibility of 99.1±1.3% with continuous-wave-mode photon pairs from the cascade-type atomic ensemble. To the best of our knowledge, this work is the first demonstration of the nonlocal two-photon interference experiment in separated photon channels by use of two-photon pairs emitted from a cascade-type atomic system as originally proposed by Franson [Phys. Rev. Lett.62, 2205 (1989)PRLTAO0031-900710.1103/PhysRevLett.62.2205].

Information theoretic analysis of hyperspectral imaging systems with applications to fluorescence microscopy.

We present a general stochastic model for hyperspectral imaging data and derive analytical expressions for the Fisher information matrix for the underlying spectral unmixing problem. We investigate the linear mixing model as a special case and define a linear unmixing performance bound by using the Cramer-Rao inequality. As an application, we consider fluorescence imaging and show how the performance bound provides a spectral resolution limit that predicts how accurately a pair of spectrally similar fluorescent labels can be spectrally unmixed. We also report a novel result that shows how the spectral resolution limit can be overcome by exploiting the phenomenon of anti-Stokes shift fluorescence. In addition, we investigate how photon statistics, channel addition and channel splitting affect the performance bound. Finally by using the performance bound as a benchmark, we compare the performance of the least squares and the maximum likelihood estimators for spectral unmixing. For the imaging conditions tested here, our analysis shows that both estimators are unbiased and that the standard deviation of the maximum likelihood estimator is consistently closer to the performance bound than that of the least squares estimator. The results presented here are based on broad assumptions regarding the underlying data model and are applicable to hyperspectral data acquired with point detectors, sCMOS, CCD and EMCCD imaging detectors.

Progress toward cryogen-free spin-photon interfaces based on nitrogen-vacancy centers and optomechanics

The implementation of quantum networks involving quantum memories and photonic channels without the need for cryogenics would be a major technological breakthrough. Nitrogen-vacancy centers have excellent spin properties even at room temperature, but phonon-induced broadening makes it challenging to interface these spins with photons at non-cryogenic temperatures. Inspired by recent progress in achieving ultra-high mechanical quality factors, we propose that this challenge can be overcome by spin-opto-mechanical transduction. We quantify the coherence of the interface by calculating the indistinguishability of the emitted photons and describe promising paths towards experimental implementation.

Wideband photonic microwave channelization and image-reject down-conversion

A wideband photonic microwave channelization and image-reject down-conversion system is proposed and experimentally demonstrated. The broadband radio frequency (RF) and electrical local oscillator (LO) signals are applied to Mach–Zehnder modulators (MZMs) and be multiplexed for channelized reference. By employing DPMZMs, different optical frequency shifting LO signals for channelization are generated. Due to the frequency difference between the modulated RF signals and frequency shifted LO signals, multichannel intermediate frequency (IF) signals can be easily separated by the followed photonic I/Q receiver. Experimental results show that the RF signal with a bandwidth of 3 GHz could be down-converted into six IF signals with the same center frequency of 750 MHz and the same bandwidth of 500 MHz. The measured spurious free dynamic range (SFDR) is 101 dB•Hz 2∕3, the passband fluctuation is less than 0.5 dB; the channel isolation is over 22 dB, and the image-rejection is over 22 dB. A QPSK vector signals with 50 Msym/s and 16.5–19.5 GHz operating frequency is successfully demonstrated using the proposed scheme, and good EVMs and constellation diagrams are obtained. The proposed photonic channelization and image-reject down-conversion system may have potential applications in the RF frontends of future systems such as broadband integrated satellite communication and multi-service wireless networks.

Controlled integration of selected detectors and emitters in photonic integrated circuits.

Integration of superconducting nanowire single-photon detectors and quantum sources with photonic waveguides is crucial for realizing advanced quantum integrated circuits. However, scalability is hindered by stringent requirements on high-performance detectors. Here we overcome the yield limitation by controlled coupling of photonic channels to pre-selected detectors based on measuring critical current, timing resolution, and detection efficiency. As a proof of concept of our approach, we demonstrate a hybrid on-chip full-transceiver consisting of a deterministically integrated detector coupled to a selected nanowire quantum dot through a filtering circuit made of a silicon nitride waveguide and a ring resonator filter, delivering 100 dB suppression of the excitation laser. In addition, we perform extensive testing of the detectors before and after integration in the photonic circuit and show that the high performance of the superconducting nanowire detectors, including timing jitter down to 23 ± 3 ps, is maintained. Our approach is fully compatible with wafer-level automated testing in a cleanroom environment.

Microwave Photonic Channelizer Based on Polarization Multiplexing and Photonic Dual Output Image Reject Mixer

Microwave photonic channelizer based on coherent frequency combs (OFCs) enables processing of ultra-wideband RF signals using low-frequency components. The channel number usually equals to the comb line number of the OFCs and the bandwidth for the microwave input is determined by the frequency spacing of the OFCs. However, the generation of coherent OFCs with large comb lines and large frequency spacing is extremely challenging, limiting greatly the potential of the OFC-based channelizer. In this paper, a microwave photonic channelizer based on polarization multiplexing and photonic dual output image reject mixing is proposed and demonstrated. A broadband signal can be divided into 8 channels using only one optical carrier and a pair of dual-polarization local oscillators (DP-LOs). Each DP-LO has only 2 spectral lines with orthogonal polarization states. In addition, by introducing a pair of OFCs with $N$ comb lines, $8N$ channels can be output. The requirement of the comb line number is efficiently reduced, and the in-band interference is greatly suppressed by introducing the polarization multiplexing and the photonic dual-output image-reject mixing. A proof-of-concept experiment is carried out. An RF signal with 9.6-GHz bandwidth centered at 14 GHz is successfully divided into 8 channels with 1.2-GHz bandwidth, and the in-band interference is effectively suppressed for each channel. In addition, RF signals with 2.4-GHz bandwidth centered at 24.8 and 30.8 GHz are also successfully channelized, respectively.

Extremely Confined Gap-Plasmon Waveguide Modes Excited by Nitrogen-Vacancy Centers in Diamonds

Quantum emitters with high emission rates and efficiently coupled to optical waveguides are in demand for various applications in quantum information technologies. Accurate positioning of a quantum emitter within a strongly confined gap-plasmon waveguide (GPW) mode would allow one to significantly enhance the decay rate and efficiency of channeling of emitted photons into the waveguide mode. Here, we present experimental results on the GPW mode excitation in a gap between a monocrystalline silver nanowire and a monocrystalline silver flake by using a single nitrogen-vacancy center in a nanodiamond. The coupled systems containing a nanodiamond and the structure supporting the GPW mode are created by a combination of electron beam lithography and nanomanipulation with an atomic force microscope (AFM). In these systems, we find decay rate enhancements of up to ∼50 and the efficiency of channeling of photons into the GPW mode of up to 82%, resulting in an exceptionally high figure-of-merit of 212 for the emit...

Cascaded downconversion interface to convert single-photon-level signals at 650 nm to the telecom band.

We present a device designed for two-step downconversion of single-photon-level signals at 650nm to the 1.5-μm band with low excess noise and low required pump power as a quantum interface between matter-qubit-based nodes and low-loss photonic channels for quantum communication networks. The required pump power for this interface is around 60% of that for a comparable conventional single-pass device, which reduces the demand on the pump laser and yields a corresponding reduction in dark counts due to inelastic pump scattering. The single-photon-level signal at 649.7nm is downconverted to the telecom band using a fiber-coupled reverse proton exchange periodically poled lithium niobate waveguide and a 2.19-μm pump laser. By testing the device in the linear regime with a classical input, we achieved 99% depletion efficiency for each stage, corresponding to an internal quantum efficiency of 63% at the optimum pump power for the complete cascaded process.

Deterministic quantum state transfer between remote atoms with photon-number superposition states

We propose a protocol for quantum networking based on deterministic quantum state transfer between distant memory nodes using photon-number superposition states (PNSS). In the suggested scheme, the quantum nodes are single atoms confined in high-finesse optical cavities linked by photonic channels. The quantum information written in a superposition of atomic Zeeman states of sending system is faithfully mapped through cavity-assisted Raman scattering onto PNSS of linearly polarized cavity photons. The photons travel to the receiving cavity, where they are coherently absorbed with unit probability creating the same superposition state of the second atom, thus ensuring high-fidelity transfer between distant nodes. We develop this approach at first for photonic qubit and show that this superposition state is no less reliably protected against the propagation losses compared to the single-photon polarization states, whereas the limitation associated with the delivery of more than one photon does not affect the process fidelity. Then, by preserving the advantages of qubits, we extend the developed technique to the case of state transfer by photonic qutrit, which evidently possesses more information capacity. This reliable and efficient scheme promises also a successful distribution of entanglement over long distances in quantum networks.

Collider production of electroweak resonances from \u03b3\u03b3 states

We estimate production cross sections for 2-body resonances of the Electroweak Symmetry Breaking sector (in WLWL and ZLZL rescattering) from γγ scattering. We employ unitarized Higgs Effective Field Theory amplitudes previously computed coupling the two photon channel to the EWSBS. We work in the Effective Photon Approximation and examine both e−e+ collisions at energies of order 1–2 TeV (as relevant for future lepton machines) and pp collisions at LHC energies. Dynamically generating a spin-0 resonance around 1.5 TeV (by appropriately choosing the parameters of the effective theory) we find that the differential cross section per unit s, pt2 is of order 0.01 fbarn/TeV4 at the LHC. Injecting a spin-2 resonance around 2 TeV we find an additional factor 100 suppression for pt up to 200 GeV. The very small cross sections put these γγ processes, though very clean, out of reach of immediate future searches.

Probing the effects of dimension-eight operators describing anomalous neutral triple gauge boson interactions at FCC-hh

The effects of dimension-eight operators giving rise to anomalous neutral triple gauge boson interactions of Zγγ and ZγZ vertices in pp→l−l+γ and pp→νν¯γ are investigated at 100 TeV center of mass energy of future circular hadron collider (FCC-hh). The transverse momentum of photon, invariant mass of l−l+γ and angular distribution of charged lepton in the rest frame of l−l+ and Missing Energy Transverse (MET) are considered in the analysis. The realistic detector effects are also included with Delphes simulation. Sensitivity limits obtained at 95% C.L. for CB˜W/Λ4 and CBB/Λ4 couplings are [−0.52;0.52]([−0.40;0.40]) TeV−4, [−0.43;0.43]([−0.33;0.33]) TeV−4 in the dilepton+photon channel and [−0.11;0.11]([−0.084;0.084]) TeV−4, [−0.092;0.092]([−0.072;0.072]) TeV−4 in the MET+photon channel with Lint=1 (3) ab−1, respectively.

Double-efficiency photonic channelization enabling optical carrier power suppression.

A novel double-efficiency photonic channelization scheme with optical carrier power suppression (OCS) is proposed for the first time, to the best of our knowledge. In this scheme, a tunable optical frequency comb generator is used to efficiently generate radio-frequency (RF) carriers, and a Fabry-Perot filter (FPF) is introduced to split a broadband signal into multiple narrowband signals. With the well-designed frequency of RF carriers, the wavelength spacing of optical carriers, and the free spectrum range of the FPF, double-channelized efficiency can be obtained. A proof-of-concept system is demonstrated to verify the feasibility of this double-efficiency channelization scheme, in which a 5GHz baseband signal is channelized into five 1GHz sub-channels, and about 35dB OCS is obtained. Moreover, the performance of the double-efficiency channelization scheme is analyzed based on a 5Gbit/s baseband signal with an on-off keying (OOK) format in which the influence of the 3rd order term interference is discussed.

Trapezoid 2D photonic crystal nanoring resonator-based channel drop filter for WDM systems

In the present work, a nanostructure of trapezoid photonic crystal ring resonator-based channel drop filter is designed for wavelength division multiplexing systems (WDM) to drop a channel at a center peak wavelength of 1543 nm. The proposed channel drop filter is composed of bus waveguide, drop waveguide, trapezoid nanoring resonator and reflector in a two-dimensional (2D) hexagonal lattice with circular rods arranged in air host. The trapezoid nanoring resonator is playing a very important role in WDM systems for dropping a single channel over a wide wavelength range. The photonic band gaps of perfect lattice structure and non-perfect lattice structure are absolutely calculated by plane wave expansion method. The functional properties of the designed filter are evaluated by finite difference time domain method (FDTD). The functional properties are center peak wavelength, dropping efficiency, passband width and quality factor. The FDTD method results show dropping efficiency is 100%, and quality factor is about 514.33 which are highly suitable for WDM systems. Further, lattice constant, inner and outer rod radius and refractive index difference of the structure are varied to tune the filter center peak wavelength and its corresponding functional parameters effects are investigated. The proposed nanoring resonator-based optical filter is ultra-compact size around $$14\, \upmu \hbox {m} \times 8.4\, \upmu \hbox {m}$$ ; hence, it is extremely suitable for WDM-based photonic communication systems and photonic integrated circuits.