Dense Wavelength Multiplexing Research Articles

Investigation of modified uni-traveling carrier photodiode for cryogenic microwave photonic links

Quantum devices present the potential for unparalleled computing and communications capabilities; however, the cryogenic temperatures required to successfully control and read out many qubit platforms can prove to be very challenging to scale. Recently, there has emerged an interest in using microwave photonics to deliver control signals down to ultracold stages via optical fiber, thereby reducing thermal load and facilitating dense wavelength multiplexing. Photodetectors can then convert this optical energy to electrical signals for qubit control. The fidelity of the quantum operations of interest therefore depend heavily upon the characteristics of the photodiode, yet experimental demonstrations of fiber-coupled photodetection systems at low temperatures are relatively few in number, leaving important open questions regarding how specific detectors may perform in real-world cryogenic settings. In this work, we examine a highly linear modified uni-traveling carrier photodiode (MUTC-PD) under C-band illumination (1530–1565 nm) at three temperature regimes (300 K, 80 K, and ∼4 K) and multiple bias conditions. Our findings of reduced responsivity but preserved bandwidth are consistent with previous studies, while our saturation tests suggest a variety of potential applications for MUTC-PDs in cryogenic microwave photonics with and without electrical bias. Overall, our results should provide a valuable foundation for the continued and expanding use of this detector technology in quantum information processing.

Optical fibres with an inscribed fibre Bragg grating array for sensor systems and random lasers

We report the latest results on inscribing extended fibre Bragg grating (FBG) arrays upon fibre drawing, obtained at the Kotelnikov Institute of Radioengineering and Electronics of RAS. The properties of these structures are considered, and examples of their application in sensor systems of microwave dense wavelength multiplexing and as a basis for designing single-frequency fibre lasers are considered. The optical and laser characteristics of FBG arrays, inscribed (using 248-nm UV laser radiation) both in standard single-mode telecommunication fibres of the SMF-28 type and in erbium-doped active fibres, are investigated.

Dual-input concave diffraction grating demultiplexer based on dielectric multidirectional reflectors

The conventional concave diffraction grating (CDG) is commonly operated as a coarse demultiplexer device due to significant increases in the chip size and cost for large dispersion. Compact dense wavelength multiplexing is proposed and demonstrated by utilizing a dual-input CDG integrated with dielectric multidirectional reflectors. This structure allows light beams incident from two different directions to be efficiently reflected and get diffracted into the respective output waveguides by a single grating, thus creating a doubled channel number and halved channel spacing while keeping the chip size constant. The dielectric multidirectional reflector is designed by one-dimensional photonic crystal theory and used as the grating tooth to provide high reflectivities over a wide angular range. Simulation results suggest that the dual-input CDG with incident angles of 1° and 6° exhibits efficiency of more than $-0.564 \,\,{\rm{dB}} $ and crosstalk less than $-21.2 \,\,{\rm{dB}} $.

Cross talk-free coherent multi-wavelength Brillouin interaction

Stimulated Brillouin scattering drives a coherent interaction between optical signals and acoustic phonons and can be used for storing optical information in acoustic waves. An important consideration arises when multiple optical frequencies are simultaneously employed in the Brillouin process: in this case, the acoustic phonons that are addressed by each optical wavelength can be separated by frequencies far smaller than the acoustic phonon linewidth, potentially leading to cross talk between the optical modes. Here we extend the concept of Brillouin-based light storage to multiple wavelength channels. We experimentally and theoretically show that the accumulated phase mismatch over the length of the spatially extended phonons allows each optical wavelength channel to address a distinct phonon mode, ensuring negligible cross talk and preserving the coherence, even if the phonons overlap in frequency. This phase-mismatch for broad-bandwidth pulses has far-reaching implications allowing dense wavelength multiplexing in Brillouin-based light storage, multifrequency Brillouin sensing and lasing, parallel microwave processing, and quantum photon-phonon interactions.

LiFi cross-connection node model using whispering gallery mode of light in a microring resonator

A free space cross-connection of the optical signals using an optical micro/nano-electro-mechanical system(OMEMS/ONEMS) is designed and simulated using the commercial software called MATLAB and OPTI-WAVE programs, in which a nonlinear micro-ring device known as a Panda-ring resonator is used to form the cross connection of two different sources, the whispering gallery modes (WGM) of those two wavelengths are multiplexed, where bandwidth capacity of the dense wavelength multiplexing can reach the Big data link criteria, in which the capacity link is up 40 PB (Petra bytes). The design device material is the AlGaAsP/InP, from which the WGM beams of the cross connection is generated within each center ring device by controlling the two coupled nonlinear side ring parameters. The cross connection of the multi-light nodes are generated and the cross-connection performed. The triple Panda-ring is embedded by the light photo-detector and source, from which the ring three input signals are modulated and input into the system and multiplexed with the previous cross connection sources. The cross-connection among the input signals via the WGMs and input signals from ring three can emerge, where finally, the cross-connected signals of them can be generated and seen at the center rings, i.e. WGM nodes and the output ports, which is allowed to have the high capacity transmission, where the use of the internet of things (IoT) is plausible.

32 channel DQPSK DWDM-PON for local area network using dispersion compensation fiber

In the contest to improving optical channel rates in dense wavelength multiplexing (DWDM) service to realize 40Gb/s, different adjustment and coherent detection plans are being investigated. In this paper, we present differential quaternary phase-shift keying (DQPSK) balance for the arrangement of a 32-channel DWDM in a Local Area Network (LAN).

KW-class direct diode laser for sheet metal cutting based on DWDM of pump modules by use of ultra-steep dielectric filters.

A direct diode laser was built with > 800 W output power at 940 nm to 980 nm. The radiation is coupled into a 100 µm fiber and the NA ex fiber is 0.17. The laser system is based on pump modules that are wavelength stabilized by VBGs. Dense and coarse wavelength multiplexing are realized with commercially available ultra-steep dielectric filters. The electro-optical efficiency is above 30%. Based on a detailed analysis of losses, an improved e-o-efficiency in the range of 40% to 45% is expected in the near future. System performance and reliability were demonstrated with sheet metal cutting tests on stainless steel with a thickness of 4.2 mm.

Dense wavelength multiplexing of 1550 nm QKD with strong classical channels in reconfigurable networking environments

To move beyond dedicated links and networks, quantum communications signals must be integrated into networks carrying classical optical channels at power levels many orders of magnitude higher than the quantum signals themselves. We demonstrate the transmission of a 1550 nm quantum channel with up to two simultaneous 200 GHz spaced classical telecom channels, using reconfigurable optical add drop multiplexer (ROADM) technology for multiplexing and routing quantum and classical signals. The quantum channel is used to perform quantum key distribution (QKD) in the presence of noise generated as a by-product of the co-propagation of classical channels. We demonstrate that the dominant noise mechanism can arise from either four-wave mixing or spontaneous Raman scattering, depending on the optical path characteristics as well as the classical channel parameters. We quantify these impairments and discuss mitigation strategies.

Tristability of a semiconductor laser due to time-delayed optical feedback

We present an experimental and theoretical study of multistability of a single-mode laser subject to feedback through phase tuning and amplifier sections integrated on the same chip. Closely above threshold, a regime of tristability of continuous-wave (CW) states is found for multiple ranges of amplifier and phase currents. The separation between the tristable wavelengths agrees with the channel spacing of dense wavelength multiplexing in the C band of optical communication making the device interesting for ternary logic applications. Complementary theoretical investigations in the framework of the paradigmatic Lang-Kobayashi model provide a consistent understanding of the experimental findings and additionally yield an analytic formula expressing the maximum number of coexisting stable CW states by the linewidth-enhancement factor alpha . Tristability belongs to the alpha range from 5 to 8 in good agreement with experiment.

On managing optical services in future control-plane-enabled IP/WDM networks

This paper presents the design and experimental implementation of a service-oriented Internet Protocol (IP)/wavelength division multiplexing (WDM) management plane. In the proposed approach, compliant with International Telecommunication Union Telecommunication Standardization Sector (ITU-T)'s automatic-switched optical network (ASON), a distributed control plane performs signaling, routing, and discovery functions, and a decentralized management plane, both at information and architectural levels, performs cross-plane actions to enforce service establishment and monitoring with a view to guarantee service level agreements (SLAs). In-service monitoring provides status of optical resources and services by using spectral- and time-domain information. Some performance aspects of the approach are evaluated in a real testbed featuring dense wavelength multiplexing and a control plane based on the Internet Engineering Task Force (IETF)'s generalized multiprotocol label switching (GMPLS).

Sinusoidally Chirped Fibre Bragg Gratings

A sinusoidal chirp structure is proposed to improve the performance offibre gratings as dispersion compensators and multichannel filters.Nearly ideal reflection spectra from sinusoidally chirped fibregratings are exhibited. The bandwidth utilization defined as the ratioof -1 dB to -30 dB bandwidths could be higher than 0.85, even up to0.985. The sinusoidal chirp can be applied to the sampled fibregratings to enhance channel uniformity. We demonstrate 141uniform channels with a 25-GHz spacing for high dense wavelengthmultiplexing applications.

Wavelength-division multiplexing of adiabaticsolitons for repeaterless transmission

Error-free repeaterless transmission of two 10 Gbit/s wavelength-division multiplexed channels over 236 km using adiabatic soliton propagation has been demonstrated. The 150 GHz optical bandwidth of each channel is converted by the adiabatic evolution to 12.5 GHz, allowing dense wavelength multiplexing. Channel separations of 100 and 675 GHz are compared.