Bilas Chowdhury

Analysis of spatial domain multiplexing/space division multiplexing (SDM) based hybrid architectures operating in tandem with wavelength division multiplexing

Spatial domain multiplexing (SDM) also known as space division multiplexing adds a new degree of photon freedom to existing optical fiber multiplexing techniques by allocating separate radial locations to different MIMO channels as a function of the input launch angle. These independent MIMO channels remain confined to the designated location while traversing the length of the carrier fiber, due to helical propagation of light inside the fiber core. The SDM technique can be used in tandem with other multiplexing techniques, such as time division multiplexing (TDM), and wavelength division multiplexing in hybrid optical communication schemes, to achieve higher optical fiber bandwidth by increasing the photon efficiency due to added degrees of photon freedom. This paper presents the feasibility of a novel hybrid optical fiber communications architecture and shows that SDM channels of different operating wavelengths continue to follow the input launch angle based radial distribution pattern.

An order of magnitude improvement in optical fiber bandwidth using spatial domain multiplexing/space division multiplexing (SDM) in conjunction with orbital angular momentum (OAM)

Spatial Domain Multiplexing/Space Division Multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single mode pigtail laser sources of same wavelength into a carrier fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. In this endeavor we launch light from five different single mode pigtail laser sources at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation we get five distinct concentric donut shaped rings with negligible crosstalk at the output end of the fiber. These SDM channels also exhibit Orbital Angular Momentum (OAM), thereby adding an extra degree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

Combining spatial domain multiplexing and orbital angular momentum of photon-based multiplexing to increase the bandwidth of optical fiber communication systems

Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single- mode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launch- ing angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation, five distinct concentric donut-shaped rings with negligible crosstalk at the output end of the fiber were obtained. These SDM channels also exhibit orbital angular momentum (OAM), thereby adding an extradegree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simu- lated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM. ©2016 Society of Photo-Optical Instrumentation

Wavelength Independency of Orbital Angular Momentum (OAM) Channels in Spatially Multiplexed Systems

The wavelength independency of OAM is presented showing that the location of spatially multiplexed (SDM) optical channels carrying OAM is independent of the wavelength of light.

Design of Portable Multiplexer for Use with Spatial Domain Multiplexed Communication Systems

A portable multiplexer for use with spatially multiplexed optical fiber communications system is presented that utilizes multiple hollow core tubes at fixed angles adding stability, reliability, robustness and ease of use to spatial multiplexers.

Spectral response of a portable multiplexer combining wavelength division multiplexing and spatially multiplexed communication architectures

This presents spectral response, experimental data and beam intensity profiles from a novel portable multiplexer unit for spatial domain/space division multiplexing in optical fibers that support hybrid optical architectures by combining spatial and wavelength division multiplexing.

Wavelength independency of spatially multiplexed communication channels in standard multimode optical fibers

Abstract. Spatial domain multiplexing (SDM), also known as space division multiplexing, adds a new degree of photon freedom to existing optical fiber multiplexing techniques by allocating separate radial locations to different channels of the same wavelength as a function of the input launch angle. These independent MIMO channels remain confined to their designated locations while traversing the length of the carrier fiber owing to helical propagation of light inside the fiber core. As a result, multiple channels of the same wavelength can be supported inside a single optical fiber core, thereby allowing spatial reuse of optical frequencies and multiplication of fiber bandwidth. It also shows that SDM channels of different operating wavelengths continue to follow an output pattern that is based on the input launch angle. As a result, the SDM technique can be used in tandem with wavelength division multiplexing (WDM), to achieve higher optical fiber bandwidth through increased photon efficiency and added degrees of photon freedom. This endeavor presents the feasibility of a hybrid optical fiber communication architecture in which the spectral efficiency of the combined system increases by a factor of “n” when each channel of an “n” channel SDM system carries the entire range of WDM spectra.