Spatial Demultiplexer Research Articles

Resource-efficient low-loss four-channel active demultiplexer for single photons

We report a design and implementation of a resource-efficient spatial demultiplexer which produces four indistinguishable photons with efficiency of 39.7% per channel. Our scheme is based on a free-space storage/delay line which accumulates four photons and releases them by a controlled polarization rotation using a single Pockels cell.

Resource-efficient low-loss four-channel active demultiplexer for single photons

We report a design and implementation of a resource-efficient spatial demultiplexer which produces four indistinguishable photons with efficiency of 39.7% per channel. Our scheme is based on a free-space storage/delay line which accumulates four photons and releases them by a controlled polarization rotation using a single Pockels cell.

Free space optical communication receiver based on a spatial demultiplexer and a photonic integrated coherent combining circuit.

Atmospheric turbulence can generate scintillation or beam wandering phenomena that impairs free space optical (FSO) communication. In this paper, we propose and demonstrate a proof-of-concept FSO communication receiver based on a spatial demultiplexer and a photonic integrated circuit coherent combiner. The receiver collects the light from several Hermite Gauss spatial modes and coherently combine on chip the energy from the different modes into a single output. The FSO receiver is characterized with a wavefront emulator bench that generates arbitrary phase and intensity patterns. The multimode receiver presents a strong resilience to wavefront distortions, compared to a monomode FSO receiver. The system is then used to detect an analog modulation of an optical beam through a random wavefront profile to mimic the transmission of a signal on a degraded optical link.

A Phase-Retrieving Coherent Receiver Based on Two-Dimensional Photodetector Array

To achieve an ultra-compact and flexible coherent transceiver solution, a carrier-less coherent detection technique using a two-dimensional (2-D) photodetector array (PDA) is proposed based on the idea of phase retrieval (PR). In the proposed PR-based coherent receiver, the optical phase information is digitally reconstructed from multiple intensity-only measurements acquired by arrayed photodetectors; neither local light sources, optical hybrids, nor spatial demultiplexers are needed. We develop a robust and low-complexity PR algorithm, which exploits prior knowledge on the optical modulation format, for the proposed PR receiver. As a proof-of-concept, the coherent detection of 10-Gbaud optical phase-modulated signals, including QPSK, 16-QAM, coherent optical OFDM, and polarization-multiplexed QPSK signals, using only a 2-D PDA is demonstrated experimentally.

Weakly-coupled 7-core-2-LP-mode transmission using commercial SFP + transceivers enabled by all-fiber spatial multiplexer and demultiplexer.

Spatial division multiplexing transmission over few-mode multicore fiber (FM-MCF) recently attracts great interests by simultaneously exploiting two more dimensions than conventional single mode fibers. In this paper, we propose an all-fiber spatial multiplexer (MUX) by cascading mode-selective fiber couplers (MSCs) with a fiber-bundle-type fan-in device, and spatial demultiplexer (DEMUX) by cascading a fiber-bundle-type fan-out device with degenerate-mode-selective fiber couplers and MSCs. Thanks to the low crosstalk of the FM-MCF, spatial MUX/DEMUX and their coupling, weakly-coupled 7-core-2-LP-mode real-time transmission over 1-km of FM-MCF is successfully demonstrated using 10-Gbps commercial enhanced small form-factor pluggable (SFP + ) transceivers.

Volume holographic spatial mode demultiplexer with a dual-wavelength method.

Volume holographic demultiplexers (VHDMs) provide spatial mode demultiplexing using simple optical systems. However, applying VHDM to practical optical communication systems is difficult, as typical holographic media have no sensitivity in the infrared region, which includes optical transmission bands. In this paper, we propose a VHDM scheme combined with a dual-wavelength method (DWM). Using the DWM, VHDMs are able to perform mode demultiplexing in the optical transmission bands. We experimentally demonstrated the basic operation of our proposal using experiments performed at an 850-nm wavelength. In addition, we performed numerical simulations to investigate the application of VHDM to the C-band.

Four-Channel Integrated Receiver with a Built-In Spatial Demultiplexer Optics for 100Gb/s Ethernet

Four-Channel Integrated Receiver with a Built-In Spatial Demultiplexer Optics for 100Gb/s Ethernet

Readdressable Interconnects With Spatial Soliton Waveguides in Liquid Crystal Light Valves

We excite spatial solitons by reorientational nonlinearity of the nematic liquid crystals, using a photoconductive light valve to implement an external light-driven control of their trajectories. Control spots provide deviations of the solitons and allow implementing various routing operations. We demonstrate 2-bit (4-output) and 3-bit (8-output) spatial demultiplexers and a continuously adjustable X/Y power-dependent junction.

Experimental Demonstration and Potential Applications of a Tunable NRI Ferrite-Wire Metamaterial

The full-wave validation and experimental demonstration of a NRI metamaterial composed of an array of dielectrically insulated metal wires embedded in a ferrite substrate are reported. The simulation and experimental setup places a wedge-shaped NRI metamaterial in a parallel-plate waveguide structure and measures the refraction angles at the output of the wedge as a function of frequency and of the applied magnetic field using a circular array of tapered transmission lines, for setup size limitation and convenient matching. Moreover, two applications related to this setup are proposed: a real-time spectrum analyzer and a spatial demultiplexer.

Investigation of multichannel spatial demultiplexer based on thickness-tapered thin film stacks

A conventional high reflectance (HR) coating sandwiched between two thickness-tapered period thin film stacks is investigated to enhance multichannel spatial dispersion, since phase shift on reflection changes rapidly due to the mismatch induced by the overlaps of different reflective bands. Compared with ordinary Bragg reflector, this structure can be more freely to enhance multichannel spatial shift. The design, fabrication and testing results of this special multichannel filter were presented in the paper, and show the potential to act as a novel demultiplexer.

Tunable spatial demultiplexer based on the Fabry-Perot filter

Superprism effect is exhibited in one-dimensional thin film stacks due to their abnormal dispersion and anisotropy properties near the bandgap. Thin film Fabry-Perot filter (FPF) was designed and fabricated to realize this effect. Furthermore, the polychromatic light was operated at different incident angles onto the device to get more demultiplexing channels at different wavelength range. This means FPF, which fabricated low-costly and simply can be used as a tunable demultiplexing device. Meanwhile, distinguished with other researchers' arithmetic, transfer matrix method (TMM) with the Gaussian angular spectrum method was introduced to calculate more accurate spatial shift at different wavelength as well as to analysis beam splitting phenomena in FPF.

Resonance-cone focusing in a compensating bilayer of continuous hyperbolic microstrip grids

We propose a periodic structure synthesized by arranging continuous transmission-line segments in a two-dimensional planar grid over a ground plane. The periodic grid exhibits hyperbolic spatial dispersion characteristics, leading to the formation of highly directive beams called “resonance cones.” Simulations and experiments at 10GHz show negative refraction and frequency-dependent spatial focusing of the resonance cones, when two such grids with compensating phase properties are interfaced to form a bilayer. The proposed structures are deprived of loading elements or vias, thus leading to ease of fabrication and scalability with frequency for applications, such as spatial filters, multiplexers, and demultiplexers.

Wavelength demultiplexer using the spatial dispersion of repeated-period double-chirped structures*

Based on the rudimentary double-chirped stack, exploiting wavelength-dependent penetration depth, repeated-period double-chirped structures, in which each couple of Bragg layers is repeated for different times, are presented to increase the spatial linear shift and the beam shifting with different incident wavelength, thus allowing the design of compact thin-film spatial wavelength demultiplexer. We compare the improved structure repeated for n times with the directly double -chirped structure with the same layer number, finding that the former has not only more advantages in theoretical design but a higher tolerance in experiment al fabrication. Besides, we have given the qualitative analysis for the strongosc illation appearing in the spatial dispersion curves when the repeated times of improved double-chirped structure or the wavelength of incident beam are relatively large.