Long range surface plasmon polariton waveguides at 1.31 and 1.55 μm wavelengths

We investigate characteristics of gold metal strip waveguides based on long range surface plasmon polaritons (LRSPPs) along thin metal strips embedded in a polymer for practical applications at the telecommunication wavelengths of 1.31 and 1.55 μm. Guiding properties of the gold strip waveguides are theoretically and experimentally evaluated with the limited thickness and width up to ∼20 nm and ∼10 μm, respectively. The lowest propagation loss of ∼1.4 dB/cm is obtained with a 14.5-nm-thick and 2-μm-wide gold strip at 1.55 μm. With a single-mode fiber, the lowest coupling loss of ∼0.4 dB/facet is achieved with a 14.5-nm-thick and 5-μm-wide gold strip at 1.55 μm. The lowest insertion losses are obtained 8-9 dB with 1.5 cm-long gold strips of a limited thickness and width at both the wavelengths. We demonstrate a 10 Gbps optical signal transmission via the LRSPP waveguide with a 14 nm-thick, 2.5 μm-wide, and 4 cm-long gold strip. These LRSPP waveguides have potential applications for optical interconnects and communications.     

Optical alignment tolerances in double-side irradiated self-written waveguide-induced fiber arrays packages

In this paper, we present our experimental study on the optical alignment tolerance between the couplings of single-mode fibers (SMFs) connected with a double-side irradiation-induced self-written waveguide (SWW). The study firstly focuses on the coupling of two SMFs and then on the two fiber arrays (FAs) for parallel optical communication. The SWW was formed in dye-dispersed epoxy materials by the photopolymerization technique. Rhodamine 6G dye was dispersed in epoxy, which is commonly used in the photonic packaging industry as a bonding adhesive. Using double-side irradiated SWW, we found the alignment tolerance for such optical interconnect to relax significantly. All the formed SWWs were evaluated in terms of optical loss. In our study, up to 4 µm misalignment tolerance was allowed for only 1 dB loss penalty. In addition, the optical interconnect formed by this technique was also able to tolerate up to ± 10 µm lateral shift with only 1 dB extra loss. The wavelength-dependent loss (from 1520 to 1610 nm) and polarization-dependent loss were less than 0.4 dB. The double-side irradiated SWW-induced couplings between two FAs also provided low optical loss. They were found to be less sensitive to temperature changes, and no significant distortion in the digital signal transmission test was observed. We believe that the findings are useful and applicable to other dye-dispersed epoxy material systems for relaxing the alignment tolerance of the optical interconnects in various photonic packaging situations.     

High-performance 850 nm vertical-cavity surface-emitting laser in Gigabit Ethernet network

High-performance oxide vertical-cavity surface-emitting (VCSEL) laser is fabricated, and its usefulness is demonstrated as a suitable transmitting light source at 850 nm operating wavelength for Gigabit Ethernet application. Utilization of barrier reduction layers reveals low-threshold current requirement for operation at high modulation bandwidth. The electrical and optical characteristics, measured from the fabricated VCSEL, are simulated for Gigabit Ethernet transmission. Data rates of 1.25 Gbps with a bit error rate of 10⁻¹¹ are achieved by the use of a specific multimode network simulator.     

Add/drop applications in fiber ring networks based on a reconfigurable optical add/drop multiplexer in a re-circulating loop

A periodic add/drop system in a fiber ring network was investigated using a reconfigurable optical add/drop multiplexer (ROADM) in a re-circulating fiber loop. After seven cascaded add/drop nodes at every 150 km along the transmission, at bit error ratio (BER) equals to 10⁻⁹ and data rate of 10 Gbps, we observed a 2.5 dB power penalty for the passing through channels with 1050 km transmission distance, and 0.3 dB sensitivity penalty variation for the periodic add/drop channels at every 150 km, respectively.     

Transmission of 4× 40/10 Gbps in a WDM-PON using NRZ-DQPSK/ASK modulation

In this paper we demonstrate the feasibility to deploy a wavelength division multiplexing passive optical network (WDM-PON) of a 30 km standard single-mode fiber (SSMF-28) carrying 160 Gbps data in downstream and 40 Gbps through the uplink. The developed method is based on the comparison between two WDM-PON systems of 4 channels with the same characteristics, using two different formats of modulation in OLTs. The first system uses the NRZ-ASK in the downlink direction, while the second uses the NRZ-DQPSK.     

Optical data timing skews in on-chip optical WDM interconnects

Micro-cavity induced optical data timing skews (ODTS) in wavelength division multiplexing (WDM) on-chip optical interconnect are investigated. In a 10 Gb/s non-return-to-zero (NRZ) WDM system, potentially 28 ps timing skews can be induced by the linewidth non-uniformities among the ring-resonator-based devices, which leads to 3.75 dB signal eye opening penalty. It is shown the coupled type filter structure can help reduce optical data timing skews.     

50 km bidirectional FTTH transmission comparing different PON standards

In this paper, a bidirectional Fiber To The Home (FTTH) is proposed where WDM transmitter is used as a seeding source with wavelength of 1550 nm. The system utilizes a Travelling wave Semiconductor Optical Amplifier (TSOA) with injection current 0.15A. 50 km range FTTH architecture is demonstrated for both downstream and upstream channels. We investigated the impact of different data rates on upstream and downstream data. The BER results show that the performance of our scheme is good for 10 Gbps system for downstream transmission as it accommodates 64 ONUs. From simulation results show the BER of 9.95e-009 is reported at 15 Gbps but only in case of 32 ONUs. Similarly, in case of upstream transmission, Q-Factor of 15.04 dB is reported for 32 ONUs. So this scheme is a practical solution to meet the data rate of the optical links simultaneously in tomorrow's PON access networks.     

Investigations on PMD-induced penalties in 40 Gbps optical transmission link

Polarization-mode dispersion (PMD) in optical fibers and components can be a limiting impairment in high-speed, long-haul transmission link. In this paper, we have carried out investigations on PMD-induced penalties in a 40 Gbps optical transmission link and we obtained results for DGD, BER, Q² (dB) for different values of the PMD coefficient and different random seeds using computer simulation.     

Reconfigurable mesh-based inter-chip optical interconnection network for distributed-memory multiprocessor system

A 4×4 reconfigurable mesh-based inter-chip optical interconnection network is reported for distributed-memory multiprocessor system and the experiment confirmed that the data rate in each channel could reach above 3.125 Gbps, which would be a good solution to solve the communication bottlenecks between processors. Each node of this reconfigurable mesh could realize 15 internal connection patterns to complete the interconnections of processors. Besides, this mesh interconnect network via ultra-high bandwidth waveguides embedded in EOPCB can realize flexible multiprocessor system architecture options.     

Fabrication and characterization of hollow metal waveguides for optical interconnect applications

As data rates continue to increase in high-performance computer systems and networks, it is becoming more difficult for copper-based interconnects to keep pace. An alternative approach to meet these requirements is to move to optical-based interconnect technologies which offer a number of advantages over the legacy copper-based solutions. In order to meet the stringent requirements of high performance and low cost, manufacturable waveguide technologies must be developed. Past solutions have often employed polymer waveguide technologies, which can be expensive and limited by modal dispersion. In the present work, hollow metal waveguides (HMWGs) are investigated as a potential alternative. These waveguides demonstrate very low optical losses of <0.05 dB/cm and the capability to transmit at extremely high data rates. The fabrication, modeling, characterization of the HMWGs are discussed to enable photonic interconnect solutions for future generations of computer and server products.     

Modeling and simulation of FBG based OCDMA-IsOWC system

Photonics have evolved from protracted fibers to dominant wireless system to look at the use of hybrid optical-wireless communication system into space technology. Inter-satellite optical wireless communication (IsOWC) systems, one of the important applications of optical-wireless communication, will be deployed in space in the near future. A significant improvement in BER at 5 Gbps is achieved along with the maximum length of ISL link between the two satellites by incorporating OFDM scheme in IsOWC systems than that of conventional IsOWC systems [9]. The work is further extended in this paper to prolong the ISL link with acceptable BER at 10 Gbps between two satellites in space by employing code division multiple access (CDMA) scheme due to its robustness against narrowband interference and an inherent low power spectral density. In this work, we have designed a model of FBG based CDMA-IsOWC system to establish a prolonged ISL link at data rate of 10 Gbps with SNR of 20 dB. Further, a comparison is also reported between our proposed FBG based CDMA-IsOWC system and OFDM-IsOWC system.     

A novel approach for simultaneous millimeter wave generation and high bit rate data transmission for Radio over Fiber (RoF) systems

We propose a novel method for simultaneous transmission of OC-192 (9.95328 Gbps) digital data and 60 GHz RF generation in a Standard Single Mode Fiber (SSMF) link utilizing Stimulated Brillouin Scattering (SBS). The system comprises of a 1550 nm DFB Laser diode, Mach Zehnder modulator (MZM), 50 km SSMF and Optical receiver. The receiver includes laser diode for optical pump, a regenerator for data retrieval and a RF bandpass filter for RF generation. This system requires minimum number of RF and optical components for the generation of 60 GHz RF. The remotely generated 60 GHz RF signal may be used for wireless transmission of data. The entire link is simulated in Optisystem software to analyze the system performance.     

A novel full duplex 16 Gbps SCM/ASK radio over fiber WDM-PON sharing wavelength for up- and down-link using bidirectional reflective filter

In this paper, a new bidirectional wavelength division multiplexing radio-over-fiber (WDM-RoF) using Subcarrier Multiplexing/Amplitude Shift Keying (SCM/ASK) is proposed which shares the same wavelengths for both up-link and down-link. A bidirectional reflective filter (BRF) is utilized in the upstream link to provide a reliable bidirectional optical channel. WDM is used to further increase the capacity of system. Simulation of the proposed scheme demonstrates 1 Gbps down- and up-link data stream for 16 channels over the length of 25 km with acceptable Q-factor (>6 dB).     

Application of Turbo codes in optical OFDM multimode fiber communication system

In this paper, Turbo Code is proposed in optical OFDM multimode fiber communication system in order to decrease the bit error rate (BER) of the system, which is mainly affected by the deep nulls of the magnitude response of multimode fiber in the high frequency region (above 3 dB). A simulation system in SIMULINK is established. Based on the system, the BER of the system with Turbo Code is compare to the systems with another two typical coding schemes including convolutional code (CC) and serially concatenated code (SCC) which uses a concatenation of convolutional and RS codes when transmitting 10 Gbps data over various length multimode fibers. Different transmitting rate is also considered. The results show that Turbo coded system has a lower BER than the other two systems and the Turbo coded system can transmit 10 Gbps data to the distance of 300 m with BER below 1e−6.     

A terabit capacity passive polymer optical backplane based on a novel meshed waveguide architecture

An optical backplane based on a meshed polymer waveguide architecture enabling high-speed board-to-board optical interconnection is presented. This planar array of multimode polymer waveguides can provide passive strictly non-blocking links between server line cards fitted with optical transmitter and receiver arrays. This architecture offers a scalable and low-cost solution to the bandwidth limitations faced by electrical backplanes and is suitable for PCB integration. The reported backplane demonstrator uses a matrix of 100 waveguides each capable of 10 Gb/s operation to interconnect 10 cards for a total capacity of a terabit per second aggregate data rate in multicast mode. Characterisation of the backplane demonstrator reveals low link losses of 2 to 8 dB for a multimode fibre input and crosstalk values below −35 dB. Error free data transmission at 10 Gb/s is achieved with a power penalty of only 0.2 dB at a bit-error-rate of 10⁻⁹. Additionally, lossless operation of a Gigabit Ethernet link over the backplane is achieved even when using the worst-case highest loss links.     

Simulation and analysis of dispersion compensation schemes for 100 Gbps PDM–OFDM optical communication system

In this paper, the implementation of 100 Gbps optical communication system exploiting polarization diversity at transmitter and receiver is developed and investigated with pre-, post- and symmetrical dispersion compensation schemes by using dispersion shifted and dispersion compensated fibers through simulations to optimize high data rate optical transmission. Motivation to the current analysis is to compare all 3 compensation schemes and it's found that the pre compensation technique is superior to post and symmetrical compensation techniques in 100 Gbps PDM–OFDM communication system. On examination of symmetrical and post dispersion compensation schemes, it's found that the later is superior to the previous in this case. A 100 Gbps coherent optical OFDM workplace has been discovered in which two 50 Gbps data streams are combined into one wavelength by polarization beam combiner. By comparing one can get a promising system to the symmetrical high capacity access network with high spectral efficiency, cost effective, good flexibility.     

Electrodeposited cobalt coating on Crofer22APU steels for interconnect applications in solid oxide fuel cells

A gas-tight cobalt-based protective coating was successfully applied by electroplating and subsequent oxidation. The coating covered all the surfaces of the machined gas channels of the metallic interconnect and adhered well to this substrate. Such a gas-tight coating offers effective blocking of Cr diffusion or evaporation from the interconnect and hence a reliable protection against Cr poisoning of the SOFC cathode. Chemical interactions were observed between the cobalt coating and the LSM contact layer, resulting in layer spallation during oxidation under pressureless conditions. Applying a pressure to the layers, spallation was effectively prevented. Although the area specific resistance (ASR) of the coated interconnect was higher than the uncoated one, it decreased steadily with time within the measurement period. The ASR was 28 mΩ cm² after an exposure of 1170 h. It seems thus that electroplating followed by oxidation is a promising method for the fabrication of spinel protective coatings for SOFC interconnects or other balance-of-plant components with complicated gas flow paths.     

Improved performance analysis of Gigabit passive optical networks

Gigabit passive optical networks (GPON) provide a capacity boosts in both the total bandwidth and bandwidth efficiency through the use of larger variable-length packets in Passive Optical Networks technology. In this paper, we have described a purely-passive GPON compatible reach extender using distributed Raman amplification and reported the improved investigation through implementation of a square root module by a distance of 60 km at data rate of 2.5 Gbps. An efficient improvement in Q factor is achieved with square root module, which further helps in increasing the length of GPON.     

On the carrier generation and HD signal transmission using the millimeter-wave radio over fiber system

The dual sideband optical carrier suppression (DSB-OCS) technique is employed in the optical carrier generation for 40 GHz radio over fiber (ROF) system. A dual electrode Mach-Zehnder modulator (DE-MZM) with the minimum transmission bias (MiTB) technique is employed to build the system. The results show that, a 40 GHz carrier is successfully generated with the amplitude up to −29 dBm and signal to noise ratio (SNR) of 35 dB and a high definition (HD) signal is successfully transmitted using the system. Finally, the bit error rate (BER) measurement is carried out for the system with 1.25 Gbps OOK signal showing an error free 40 GHz ROF system with almost no penalty between the back to back and 20 km fiber for a BER of 10⁻⁹.     

Two-Dimensional Alignment-Free Optical Interconnect Using Micro Optical Bench Scheme

In this paper, we have proposed and demonstrated a novel packaging method involving a vertical cavity-surface emitting laser (VCSEL) array. The concept is based on micro optical bench (MOB) placing a laser sub-mount and two-dimensional optical fiber array to match the reference plane of MOB to provide an alignment free optical interconnect. No degradation of I-V and I-L characteristics of the packaged VCSELs was found after use of the proposed packaging process. The coupling loss was about 0.9 dB for λ = 1.55 μm and the loss deviation among channels was less than 0.5 dB in a 2 x 4 ch coupling module between planar microlens and multi-mode fibers.