Photonic Routing Research Articles

Reconfigurable photonic routers based on multimode interference couplers

We present a design approach for compact reconfigurable light routers with N access waveguides (WGs) based on multimode interference (MMI) couplers. The proposed devices comprise two MMI couplers, which are employed as power splitters and combiners, respectively, linked by an array of N single-mode WGs. When the effective refractive index of the WGs is modulated with the proper relative optical phase difference, the light can switch paths between the preset output channel and the remaining output WGs. Taking advantage of the transfer phases between the access ports of the MMI couplers, we derive very simple phase relations between the modulated WGs that enable the reconfiguration of the output channel distribution when the appropriate coupling lengths of the MMI couplers are chosen. In this way, very compact expressions for calculating the channel assignment of the devices as a function of the applied phase shift are derived for the general case of N access WGs. Moreover, the situation where the applied phase shift varies sinusoidally, as in acoustically driven devices, is discussed. A transfer matrix formalism is employed to calculate the transmission properties of the routers. In particular, devices with six and seven access WGs are thoroughly described.

All-optical router at single-photon level by interference

The realization of the all-optical router with multiple input ports and output ports will have direct application to achieve the quantum network. We present a scheme of all-optical routing of coherent-state photons in a waveguide-cavity coupled system. Our router has four input ports and four output ports. The routing of photons is based on the interference. The outcomes show that the transport of the coherent-state photons injected through any input port can be controlled by the phases of the coherent-state photons injected through other input ports. This control can be realized at the single-photon level and requires no additional control fields. Therefore, the all-optical routing at single-photon level can be achieved.

Tunable Optomechanically Induced Absorption in a Hybrid Optomechanical System

We study the tunable optomechanically induced absorption (OMIA) with the quantized field in the system, which consists of a driven cavity and a mechanical resonator with a super-conducting charge qubit via Jaynes-Cummings interaction. Such a OMIA can be achieved by controlling the strength of the Jaynes-Cummings interaction. Moreover, our work shows this OMIA for the quantized fields can be robust against cavity decay in somehow. With the combination of optomechanically induced transparency (OMIT), our proposal may have paved a new avenue towards quantum photon router.

On-chip electrically controlled routing of photons from a single quantum dot

Electrical control of on-chip routing of photons emitted by a single InAs/GaAs self-assembled quantum dot (SAQD) is demonstrated in a photonic crystal cavity-waveguide system. The SAQD is located inside an H1 cavity, which is coupled to two photonic crystal waveguides. The SAQD emission wavelength is electrically tunable by the quantum-confined Stark effect. When the SAQD emission is brought into resonance with one of two H1 cavity modes, it is preferentially routed to the waveguide to which that mode is selectively coupled. This proof of concept provides the basis for scalable, low-power, high-speed operation of single-photon routers for use in integrated quantum photonic circuits.

Integrated Source of Spectrally Filtered Correlated Photons for Large-Scale Quantum Photonic Systems

We demonstrate the generation of quantum-correlated photon-pairs combined with the spectral filtering of the pump field by more than 95dB using Bragg reflectors and electrically tunable ring resonators. Moreover, we perform demultiplexing and routing of signal and idler photons after transferring them via a fiber to a second identical chip. Non-classical two-photon temporal correlations with a coincidence-to-accidental ratio of 50 are measured without further off-chip filtering. Our system, fabricated with high yield and reproducibility in a CMOS process, paves the way toward truly large-scale quantum photonic circuits by allowing sources and detectors of single photons to be integrated on the same chip.

Photonic router is a step toward quantum computing

Photonic router is a step toward quantum computing

Quantum optics. All-optical routing of single photons by a one-atom switch controlled by a single photon.

The prospect of quantum networks, in which quantum information is carried by single photons in photonic circuits, has long been the driving force behind the effort to achieve all-optical routing of single photons. We realized a single-photon-activated switch capable of routing a photon from any of its two inputs to any of its two outputs. Our device is based on a single atom coupled to a fiber-coupled, chip-based microresonator. A single reflected control photon toggles the switch from high reflection (R ~ 65%) to high transmission (T ~ 90%), with an average of ~1.5 control photons per switching event (~3, including linear losses). No additional control fields are required. The control and target photons are both in-fiber and practically identical, making this scheme compatible with scalable architectures for quantum information processing.

Single-photon quantum router with multiple output ports.

The routing capability is a requisite in quantum network. Although the quantum routing of signals has been investigated in various systems both in theory and experiment, the general form of quantum routing with many output terminals still needs to be explored. Here we propose a scheme to achieve the multi-channel quantum routing of the single photons in a waveguide-emitter system. The channels are composed by the waveguides and are connected by intermediate two-level emitters. By adjusting the intermediate emitters, the output channels of the input single photons can be controlled. This is demonstrated in the cases of one output channel, two output channels and the generic N output channels. The results show that the multi-channel quantum routing of single photons can be well achieved in the proposed system. This offers a scheme for the experimental realization of general quantum routing of single photons.

On-chip generation and guiding of quantum light from a site-controlled quantum dot

We demonstrate the emission and routing of single photons along a semiconductor chip originating from carrier recombination in an actively positioned InAs quantum dot. Device–scale arrays of quantum dots are formed by a two–step regrowth process. We precisely locate the propagating region of a unidirectional photonic crystal waveguide with respect to the quantum dot nucleation site. Under pulsed optical excitation, the multiphoton emission probability from the waveguide's exit is 12% ± 5% before any background correction. Our results are a major step towards the deterministic integration of a quantum emitter with the waveguiding components of photonic quantum circuits.

Long-Reach λ-Tunable WDM/TDM-PON Using Synchronized Gain-Clamping SOA Technology [Invited

This paper proposes a 40  Gbit/s class λ-tunable wavelength division multiplexing and time division multiplexing passive optical network (WDM/TDM-PON) system that uses our newly developed high-output-power λ-selective burst-mode transmitter (B-Tx) in an ONU and a 4×4 cyclic arrayed waveguide grating as a photonic router. Our developed B-Tx utilizes a booster semiconductor optical amplifier that employs a pattern effect suppression technique incorporating synchronized gain-clamping light injection, and it obtains a high output power of over +10  dBm without signal waveform distortion at all wavelength channels. We demonstrate a 40  Gbit/sλ-tunable WDM/TDM-PON that achieves a 40 km transmission reach and a 40 dB loss budget.

Quantum routing of single photons with a cyclic three-level system.

We propose an experimentally accessible single-photon routing scheme using a △-type three-level atom embedded in quantum multichannels composed of coupled-resonator waveguides. Via the on-demand classical field being applied to the atom, the router can extract a single photon from the incident channel, and then redirect it into another. The efficient function of the perfect reflection of the single-photon signal in the incident channel is rooted in the coherent resonance and the existence of photonic bound states.

Entangled mechanical cat states via conditional single photon optomechanics

We study single photon optomechanics conditioned on photon counting events. By selecting only detection events that occur long after a photon pulse arrives at the cavity, the optomechanical interaction time can be increased, allowing a large momentum kick to be applied to the oscillator. We apply this to two optomechanical cavities set-up within a Mach–Zhender interferometer driven by a single photon source. The conditional state of the mechanical modes in such a system becomes an entangled cat state for detection times resulting in maximum mechanical amplitude in phase space. Further we study the dynamics induced by a second photon pulse injected into an already conditioned optomechanical cavity, a quarter of a mechanical period after the first photon has been detected. We illustrate how the optomechanical interaction resulting from the second photon can be strongly suppressed allowing conditional optomechanical routing of single photons with single photon control pulses.

Proposal of Optical Waveguide Circuits for Recognition of Optical QAM Codes

Optical processing of optical labels at high-bit rate is expected in broadband photonic label routers. So far, a variety of optical waveguide circuits and systems to recognize optical BPSK and QPSK coded labels have been studied. In this paper, we propose optical waveguide circuits to recognize optical 16QAM codes. The circuits consist of multi-stage connection of previously proposed circuit for QPSK code recognition. The recognition characteristics for 16QAM codes are theoretically analyzed. To confirm the recognition principle, FD-BPM simulation is performed with a two-dimensional model. Scaled circuits for recognition of 2-symbol 16QAM coded labels and 64QAM codes are also discussed.

Optical Label Routing Processing for BPSK Labels Using Complex-Valued Neural Network

Optical neural-network circuit to recognize BPSK labels for photonic label routing is proposed, whose neuron consists of optical amplitude amplifiers and phase shifters as weighting connections, a combiner and a nonlinear threshold device for an activation function. The parameters of these weighting connections are learned with back-propagation of teacher signals. The performance of the neural network circuits as recognition of two to four bit BPSK labels is clarified by computer simulation. For routing application, classification of routing labels into several groups corresponding to the output ports of the router is also discussed and is successfully simulated.

Ultrawide-band photon routing based on chirped plasmonic gratings

We report an ultrawide-band photon routing based on a chirped plasmonic grating, which consists of a gold film coated with a chirped dielectric grating made of organic polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]. The photon routing is realized based on rainbow-trapping like effect. An ultrawide operating bandwidth of 200 nm is reached through scanning near-field optical microscopy measurement. The tunable photon routing is reached through adjusting structural parameters of chirped plasmonic grating or using a pump light. A shift of 0.5 μm in the terminal channel is achieved for the 850-nm incident laser when the groove width changes from 150 to 180 nm.

Spin-based Optomechanics with Carbon Nanotubes

A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing.

Nanoscale solid-state single photon router

A novel scheme for a solid-state single-photon router based on a single quantum dot (QD) coupled to a nanomechanical resonator (NR) is proposed and analyzed theoretically. It relies on the coherent coupling between the quantum dot and the NR. We demonstrate that when a single-photon signal is tuned on resonance with the exciton in the QD, one can use a strong pump field to choose to what output port of this signal field is delivered, which is based on the analogue of electromagnetically induced transparency (EIT) effect which we refer it as phonon induced transparency (PIT) in this coupled system. The path between the reflection output port and the transmission output port can be achieved by simply turning off and on the pump field. The numerical results also indicate that this router can operate efficiently in the optical regime and at ultralow pump power as well as short switching time (∼ns). This nanoscale router presented here will offer potential applications in scalable solid-state quantum networks and quantum information.

Single Photon Router in the Optical Regime Based on a Cavity Optomechanical System With a Bose–Einstein Condensate

We propose a novel scheme of a single photon router based on a coupled Bose-Einstein condensate cavity system. The numerical results obtained show that by controlling the route of the probe photon using an appropriate pump beam, this coupled system can serve as a single photon router. Importantly, this router works well in the optical regime, instead of the microwave regime, and at an ultralow pump power. The scheme, proposed here, may have potential applications in optical signal processing, communication, and quantum information networks.

Integrated Diamond Networks for Quantum Nanophotonics

We demonstrate an integrated nanophotonic network in diamond, consisting of a ring resonator coupled to an optical waveguide with grating in- and outcouplers. Using a nitrogen-vacancy color center embedded inside the ring resonator as a source of photons, single photon generation and routing at room temperature is observed. Furthermore, we observe a large overall photon extraction efficiency (10%) and high quality factors of ring resonators (3200 for waveguide-coupled system and 12,600 for a bare ring).

Integrated phased‐array switches for large‐scale photonic routing on chip

AbstractIntegrated phased‐array optical switches, having a high port‐count scalability and broad spectral coverage, can potentially be used as building blocks of large‐scale optical routers. In this article, recent works on monolithically integrated InP phased‐array switches and their applications to optical packet switching (OPS) are reviewed. After describing the theory of integrated phased‐array switches, experimental results on a single‐stage 1 × 16 switch, which features wavelength‐independent nanosecond switching characteristics, are presented. A series of OPS experiments, employing high‐bit‐rate optical packets with different modulation formats and a tunable optical buffering experiment are presented as potential applications of these switches. Finally, a large‐scale monolithic switch with as many as 100 ports is realized on a single photonic integrated circuit by cascading the phased‐array switches.