Radio Over Fiber System for A Four-Store Hospital Building

The goal of this project is to design and analyse a radio over fibre system for a four-story hospital with 20 rooms on each floor. The number of ONUs per floor is 20, and it was assumed that each room had an ONU capable of providing network access to voice, data, video, and biometrics. We build an 80-channel WDM optical transmitter using the WDM method. The proposed system includes a transmitter with 20 input channels, a multiplexer, a DE multiplexer, a 45-kilometer optical fibre, and an amplifier. The proposed model was simulated, and the results were evaluated in WDM systems using an optical amplifier. The receiver performance analysis of the Optical Communication System is shown by the BER simulation run and the eye diagram graphic, with the threshold set at 0.00120739. Furthermore, the eye height is 0.00141402, and the minimum BER is 5.59009e-006. When the simulated and calculated values of received power and total power loss are compared, the system is efficient. Keywords: Radio over fibre, Optical Amplifier, WDM system, DE multiplexer, Multiplexer, BER, Optical transmitter

A 25 Gbps VCSEL driving ASIC: an attempt for ultra-high-speed front-end readout applications

This paper presents the design and the test results of a 25 Gbps VCSEL driving ASIC fabricated in a 55 nm CMOS technology as an attempt for the future very high-speed optical links. The VCSEL driving ASIC is composed of an input equalizer stage, a pre-driver stage and a novel output driver stage. To achieve high bandwidth, the pre-driver stage combines the inductor-shared peaking structure and the active-feedback technique. A novel output driver stage uses the pseudo differential CML driver structure and the adjustable FFE pre-emphasis technique to improve the bandwidth. This VCSEL driver has been integrated in a customized optical module with a VCSEL array. Both the electrical function and optical performance have been fully evaluated. The output optical eye diagram has passed the eye mask test at the data rate of 25 Gbps. The peak-to-peak jitter of 25 Gbps optical eye is 19.5 ps and the RMS jitter is 2.9 ps.

LDLA14: a 14 Gbps optical transceiver ASIC in 55 nm for NICA multi purpose detector project

This paper presents the design and test results of a 14 Gbps optical transceiver ASIC (LDLA14) fabricated in a 55 nm CMOS technology for NICA Multi Purpose Detector (MPD) project. The LDLA14 is a single-channel bidirectional (1Tx + 1Rx) optical transceiver ASIC, including a Laser Driver (LD) module and a Limiting Amplifier (LA) module. It would drive the Vertical Cavity Surface Emitting Laser (VCSEL) of Transmitter Optical Sub-Assembly (TOSA) and receive signals from Photo Diode (PD) of Receiver Optical Sub-Assembly (ROSA), respectively. In the LDLA14, a novel structure of capacitive coupling pre-emphasis is proposed in the output driver of LD to obtain peaking effect without sacrifice the modulation current swing. A shared inductor technology and a Continuous Time Linear Equalizer (CTLE) pre-emphasis structure are added in the output buffer of LA to improve the quality of the output eye diagram. The dimension of LDLA14 is 1.5 mm × 1.3 mm, and the power consumption is 178 mW. The Peak-to-Peak Jitter (PPJ) and Root-Mean-Square Jitter (RMSJ) of the 14 Gbps optical eye diagram of LD in the Tx direction are 22.5 ps and 3.5 ps, respectively. The PPJ and RMSJ of the 14 Gbps electrical eye diagram of LA in the Rx direction are 23.1 ps and 4.7 ps, respectively. The BER tests have been conducted in Tx, Rx directions and the Tx-Rx loop condition, and the BER less than 10−12 is achieved in all tests.

GaN-Based Resonant-Cavity Light-Emitting Diodes Grown on Si

GaN-on-Si resonant-cavity light-emitting diodes (RCLEDs) have been successfully fabricated through wafer bonding and Si substrate removal. By combining the chemical mechanical polishing technique, we obtained a roughness of about 0.24 nm for a scan area of 5 μm × 5 μm. The double-sided dielectric distributed Bragg reflectors could form a high-quality optical resonant cavity, and the cavity modes exhibited a linewidth of 1 nm at the peak wavelength of around 405 nm, corresponding to a quality factor of 405. High data transmission in free space with an opening in the eye diagram was exhibited at 150 Mbps, which is limited by the detection system. These results showed that GaN-based RCLEDs grown on Si are promising as a low-cost emitter for visible light communications in future.

Comparison of RZ and NRZ Modulation Techniques by Varying Duty Cycle and Mach Zehnder Modulator

The aim of the research being undertaken is to examine the performance of advanced modulation formats such as RD and NRZ modulation schemes and their long-haul repeater-free fibre-traffic (SMF). Modular transmission of signals by SMF has been highly attracted by several benefits, such as high chromatic dispersion tolerance (CD), simplicity of deployment and higher spectrum efficiencies. These are the essential performance indicators of an optimal modulation technique for the creation of multiplexed (DWDM) transmission networks of the future generation of dense wavelengths. Based on a comparison of the two modulation approaches I give my findings. To mimic both modulation schemes, OptiSystem software is employed. Eye diagram with measurement of the Q factor and BER is generated. Keywords: Return to Zero, Non-Return to Zero, Eye Diagram, Bandwidth, BER, Q factor.

Optical SNR estimation using machine learning

A technique for the estimation of an optical signal-to-noise ratio (OSNR) using machine learning algorithms has been proposed. The algorithms are trained with parameters derived from eye-diagram via simulation in 10 Gb/s On-Off Keying (OOK) nonreturn-to-zero (NRZ) data signal. The performance of different machine learning (ML) techniques namely, multiple linear regression, random forest, and K-nearest neighbor (K-NN) for OSNR estimation in terms of mean square error and R-squared value has been compared. The proposed methods may be useful for intelligent signal analysis in a test instrument and to monitor optical performance.

A Qualitative Validation of Two Diagrammatic Measures of Attachment Network Structure

In two qualitative evaluation studies, we explored the construct validity of two diagrammatic measures of attachment network structure, including the Bull’s Eye diagrammatic technique and a significantly modified version, the Web-based Hierarchical Mapping Technique (WHMT). In the first study, 20 young adults completed a Bull’s Eye diagram followed by a semi-structured interview in which participants explained their placement of support figures in their diagrams. Interview transcripts were analyzed using theory-driven thematic analysis to determine the presence of attachment-related themes, including safe haven, secure base effect, and proximity maintenance. Findings indicated mixed support for the Bull’s Eye as a measure of attachment networks. Although attachment themes were dominant among participants who identified a parent as their primary attachment figure, this was not the case among participants who identified a peer as a primary attachment figure. Participant justifications for peer attachments relied on non-attachment themes, including identity exploration and companionship. In the second study, we applied the same qualitative method to investigate the WHMT. Saturation was reached sooner, and attachment themes were dominant for both parent and peered primary attachment. Findings support the construct validity of the WHMT as a new measure of attachment network composition and strength.

Simulation of two dimensional OCDMA-PON system based on FBGs

In order to study the effect of transmission distance on the performance of optical code division multiplexing passive optical network systems based on fiber Bragg Grating (FBG), a two-dimensional OCDMA-PON system based on cascaded FBGs is designed and constructed by using the VPI optical communication software. The spectrum, waveform and eye diagram of the output signal are analyzed by setting different fiber lengths in the system. The experimental results show that different fiber lengths have different effects on the system. Within a certain transmission distance, the longer the fiber length, the smaller the error generated by the output signal and the better the signal quality; beyond this certain distance, the quality of the output signal deteriorates sharply and the error generated becomes larger.