Pulse width shortening combinations (PWSC) for ultra-dense WDM systems and calculation of PWSE

Optical communication systems introduced paradigm shift in the forte of data transmission at higher speeds and over longer distances where, on contrary electrical transmission systems failed due to higher amplitude degradation, interferences and lower bandwidths. However, pulse width increase (PWI) in the optical fiber limits the overall distance reach and also introduces more bit errors which needs to addressed. So far, pulse width shortening fibers (PFs) and fiber Bragg grating (FG) used individually in most of the reported studies, however pulse width shortening (PWS) took either high cost (in PFs) or lower PWS efficiency (PWSE) (in FG). Therefore, in this research manuscript, we made emphasis on the combined PWS effects of diverse techniques such as optical phase conjugation (OC), FG and PFs in ultra-dense wavelength division multiplexing (WDM) system. Total link length of 400 km has been covered in 128 channels ultra dense wavelength division multiplexing (UDWDM) system at 10 Gbps by incorporating diverse combined organized placements of FG, OC and PFs such as FG-PF, OC-PF and FG-PF-OC. Results revealed that economical and maximum PWSE arrangement for proposed system is FG-PF-OC.

Physical Layer Components Security Risks in Optical Fiber Infrastructures

Optical fiber communications are essential for all types of long- and short-distance transmissions. The aim of this paper is to analyze the previously presented security risks and, based on measurements, provide the risk level evaluation. The major risk is the possibility of inserting a splitter into the optical distribution network and capturing a portion of the entire spectrum, i.e., all channels in the optical fiber. Another significant security risk is crosstalk on multiplexers in networks with wavelength division multiplexing. The paper covers the macrobend attenuation evaluation of fiber and back-reflection measurements. Based on the measurements, risks were evaluated for both point-to-point and point-to-multipoint networks and, lastly, the paper covers crosstalk measurements of an optomechanical switch. Finally, all individual risks are evaluated according to the severity, and a proposal for risk minimization is provided.

Small-Signal Analysis of All-Si Microring Resonator Photodiode

All-silicon microring resonator photodiodes are attractive for silicon photonics integrated circuits due to their compactness, wavelength division multiplexing ability, and the absence of germanium growth. To analyze and evaluate the performance of the microring photodiode, we derived closed-form expression of the response transfer function with both electrical and optical behavior included, using a small-signal analysis. The thermo-optic nonlinearity resulting from optical loss and ohmic heating was simulated and considered in the model. The predicted response achieved close agreement with the experiment results, which provides an intuitive understanding of device performance. We analytically investigated the responsivity–bandwidth product and demonstrated that the performance is superior when the detuning frequency is zero.

Rapidly Tunable Microring Filters for Optical Add-Drop (Project Report CIAN2-1-Y5)

This was a project under the Thrust 2 “Subsystem Integration and Silicon Nanophotonics” of the NSF-funded Center. The goal of this research was to design, fabricate and test microchip-scale silicon photonic components for optical WDM (wavelength division multiplexed) add/drop functionality in access and data networks. This chip was intended for use in a campus ring network.

PR34 The Case for Programmable Front-End Devices for Disaggregated Optical Networks Using Silicon Photonics (1525090-Y4)

We have studied how short-distance, wavelength division multiplexed optical communication networks can be improved by enabling programmability and user-defined tunability in the optical front-ends using silicon photonics. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1525090 (Year 4).

High Dynamic Range Variable Optical Attenuation (Project Report CIAN2-1-Y5)

The goal of this project was to design silicon photonic components for optical WDM (wavelength division multiplexed) add/drop functionality in access and data networks. One of the key functionalities that was required by the campus networking testbed was to control the optical power levels in the WDM network of each channel without requiring separate components. This was most easily achieved by integrating the Variable Optical Attenuator (VOA) functionality together with the add-drop functionality on the same photonic chips.

Opto-Mechatronics System for Train-Track Micro Deformation Sensing

In this paper, we proposed and experimentally demonstrated an opto-mechatronics system to detect the micro-deformation of tracks caused by running trains. The fiber Bragg grating (FBG) array acting as sensing elements has a low peak reflectivity of around −40 dB. The center wavelengths were designed to alternate between 1551 nm and 1553 nm at 25 °C. Based on dual-wavelength, wavelength-division multiplexing (WDM)/time-division multiplexing (TDM) hybrid networking, we adopted optical time-domain reflectometry (OTDR) technology and a wavelength-scanning interrogation method to achieve FBG array signal demodulation. The field experimental results showed that the average wavelength shift of the FBG array caused by the passage of the lightest rail vehicle was −225 pm. Characteristics of the train-track system, such as track occupancy, train length, number of wheels, train speed, direction, and loading can be accurately obtained in real time. This opto-mechatronics system can meet the requirements of 600 mm spatial resolution, long distance, and large capacity for monitoring the train-track system. This method exhibits great potential for applications in large-scale train-track monitoring, which is meaningful for the safe operation of rail transport.

Protection Scheme for a Wavelength-Division-Multiplexed Passive Optical Network Based on Reconfigurable Optical Amplifiers

This paper demonstrates a wavelength-division-multiplexed passive optical network (WDM-PON) scheme based on novel reconfigurable optical amplifiers (ROAs). The measured switching characteristics of the ROA3 constructed with a 2 × 2 crossbar optical switch and a four-port reversible optical circulator (OC) and a conventional EDFA can meet the requirements of most network management and surveillance. The self-made four-port reversible OC’s response time is less than 2 ms, and its insertion losses are about 1 dB or less for all the transmission paths and switching states. An optimal design of ROAs is proposed and evaluated for bidirectional optical amplifier protection, in which ROA3 has an EDF length of 7.5 m long with a 1480 nm pump laser and possesses a backward or forward pumping configuration with the corresponding pump power of 200 mW or 50 mW. We verified the scheme’s feasibility through a simulation of WDM-PON systems with 40 downstream and upstream channels. This scheme enables the intelligent protection switching in practical operation scenarios for high-capacity multi-wavelength networks.