A tunable intracavity fiber laser has been widely used for gas sensing. In order to design a better performance sensor by use of this tunable intracavity fiber laser, the influence factors, including output power such as pump power, intracavity loss, output splitting ratio, and emission wavelength, are investigated based on a theoretical model using the propagation equation. The tunable intracavity fiber laser is set up, and the effects of pump power, intracavity loss, output splitting ratio, and emission wavelength are measured. The experimental results indicate that the theoretical analysis is in good agreement with the experimental measurements; in the process of designing the sensor, the intracavity loss and splitting ratio should be given more attention.
Detection of pollution gas is important in environmental and pollution monitoring, which can be used widely in mining
and petrochemical industry. Fiber optical spectrum absorption (FOSA) at near-IR wavelength is widely used in gas
detection due to its essential advantages. It has attracted considerable attention, and there are several types and methods
in FOSA. Wavelength modulation technique (WMT) is one of them, which will improve the gas detection sensitivity
dramatically. This technique can be realized by detecting the intensity of the second-harmonic component signal.
Intra-cavity laser spectroscopy (ICLS) is another alternative technique for high sensitivity absorption measurement. With
an absorber directly placed within the laser cavity, a short absorption cell can be transformed into a high sensitivity
system. But the practical sensitivity is obviously less than the theoretical value. The authors did some works in these
fields and have obtained some remarkable progress. With broad reflectors instead of FBG as mirror of the cavity and
wavelength sweep technique (WST), several absorption spectra of detected gas can be collected. And the detection
sensitivity can be enhanced sharply by averaging the results of each spectrum, with acetylene sensitivity less than
100 ppm . When ICLS is used combined with WST and WMT, the detection sensitivity of acetylene can be enhanced
further. The sensitivity is less than 75 ppm. By using FBGs as wavelength references, the absorption wavelength of the
detected gas is obtained, which can be used to realize gas recognition. The system is capable of accessing into fiber
intelligent sensing network.
In this paper, an electronic speckle-shearing pattern interferometer with pulsed laser and pulse frequency controller
is fabricated. The principle of measuring the vibration in the object using electronic stroboscopic speckle--shearing
pattern interferometer is analyzed. Using a metal plate, the edge of which is clamped, as an experimental specimen,
the shear interferogram are obtained under two experimental frequencies, 100 Hz and 200 Hz. At the same time, the
vibration of this metal plate under the same experimental conditions is measured using the time-average method in
order to test the performance of this electronic stroboscopic speckle-shearing pattern interferometer. The result
indicated that the fringe of shear interferogram become dense with the experimental frequency increasing. Compared
the fringe pattern obtained by the stroboscopic method with the fringe obtained by the time-average method, the
shearing interferogram of stroboscopic method is clearer than the time-average method. In addition, both the
time-average method and stroboscopic method are suited for qualitative analysis for the vibration of the object. More
over, the stroboscopic method is well adapted to quantitative vibration analysis.
In the optical rotary joints, the Dove Prism is employed to rotate an image about the optical axis and compensate optical
path of optical signals so that the optical signals can be transferred across the rotating interface. However, manufacturing
errors and assembling errors of Dove Prism will affect the coupling efficiency of Dove Prism. In this paper, the analytical
expressions for errors of the rotating coupling efficiency are presented when the prism is manufactured with errors in its
base angle and pyramidal angle. The analytical result showed that the coupling losses that arise from manufacturing errors would increase as the base angles deviate from the traditional value of 45° and the pyramidal angle increase. At the same time, the influence of assembling errors on coupling efficiency is also analyzed using the method of light ray tracing. The assembling errors of Dove Prism included angular tilt misalignment, height misalignment, and inclining misalignment. The results indicated that these misalignments cause the coupling efficiency of Dove Prism decreased. The coupling efficiency is more sensitive to the height misalignment and angular tilt misalignment than the inclining misalignment.
Distributed stress sensor with a scanning Michelson white light interferometer can be used to detect stress distribution
and its value by analyzing polarization mode coupling caused by stress field in PMFs (polarization maintaining fibers).
In the measurement of polarization coupling, the birefringence in sensing fiber is usually considered to be
wavelength-independent. The spatial resolution of the distributed stress sensor is invariable, when the optical source
spectrum is given. In practical measurement, however, the birefringence in PMF is related with optical wavelength, the
birefringence dispersion exists in PMF. Due to the birefringence dispersion, the spatial resolution of the distributed stress
sensor descends obviously with the fiber length increasing. In this paper, the influence of external force position and
optical source spectrum on spatial resolution in the distributed stress sensor is analyzed, while the birefringence
dispersion is considered.
A white light interferometer is designed to measure the distributed polarization coupling (DPC) in
polarization-maintaining fiber (PMF). By using a Michelson interferometer to compensate the optical path difference
induced by the modal birefringence of PMF, both the coupling strength and position of the coupling point can be
acquired. The two reflective mirrors on the fixed and scanning arms should be vertical to each other. But in practice, the
movable reflective mirror can't be vertically aligned exactly to the fixed mirror, which would lead to angle misalignment.
The angle misalignment would induce the variance of the optical path difference (OPD), which would reduce the fringe
visibility. Finally, the angle error would lead to a decrease on the signal noise ratio (SNR) and miscalculation of the
polarization coupling intensity. The angle misalignment and diameter of the incident light beam both have an effect on
the fringe visibility. The simulation results show that the requirement of angle error becomes stricter with the increasing
of the light beam diameter. To decrease the angle misalignment, the two plane reflective mirrors should be replaced with
the corner cube prisms. A revised coupling strength calculation equation was proposed to minimize the influence of angle
misalignment.
One of the key issues in establishing an optical fiber sensing system based on fiber Bragg gratings (FBGs) is the
selection of a suitable wavelength shift detection scheme in terms of the performance it offers. By use of a compact
Fabry-Perot (F-P) tunable filter, the Bragg wavelength variation can be detected with a relatively high speed and
satisfying resolution. In this paper, a dynamic strain sensing system based on F-P tunable filter is described, and the F-P
tunable filter is demonstrated to have a significant impact on the system. The relationship between the collected spectrum
of grating and the 3-dB bandwidth of the F-P tunable filter is discussed. The optimum 3-dB bandwidth of the F-P tunable
filter for most FBGs is obtained. It is exhibited in this paper that the demodulation precision and sensitivity of the strain
sensing system is influenced by the nonlinearity between the transmission wavelength of the F-P tunable filter and the
drive voltage. The drive voltage is rectified using interpolation algorithm. The experimental results illustrate that the
average error and the maximum error of the transmission wavelength are decreased by 96.4% and 80.9% respectively.
The strain sensitivity of the optimized system is below
3με. The error between the practical strain value demodulated
by the system and theoretical value is below 5%.
We experimentally demonstrate a 4×10-Gb/s optical multicast scheme using a semiconductor optical amplifier (SOA)
and a single optical source, which produce a 10-GHz multi-wavelength pulse-trains used as the probe light of the SOA.
The multicast principle is based on the multi-wavelength conversion (MWC) by means of the interaction of both cross
gain modulation (XGM) and transient cross phase modulation (T-XPM) of the SOA. Because of the nonlinear
amplification of SOA, the 4 output copies are regenerated with respect to the input degraded signal. This scheme is very
simple and allows photonic integration.
We demonstrate a novel 40-Gb/s all-optical serial to parallel converter (AOSPC), which can convert 40-Gb/s serial
optical signals to 4-channel 10-Gb/s parallel optical signals. Moreover, based on the sequential multi-wavelength
conversion the AOSPC shows the regeneration ability.
We present a compact short pulses source, in which the pulses generated by large-signal directly modulated laser diode
are phase-modulated, and it can compress the pulse from 30ps to 5.3ps with 184fs timing jitter.
A white light interferometer is developed to measure the distributed polarization coupling in high-birefringence polarization-maintaining fibers (PMFs). Usually the birefringence dispersion between two orthogonal eigenmodes of PMFs is neglected in such systems. Theoretical analysis and experimental results show that the birefringence dispersion becomes a nonnegligible factor in a long-fiber test. Significant broadening of interferograms and loss of longitudinal coherence are observed. The spatial resolution and measurement sensitivity of the system decrease correspondingly. Optimum spectrum width selection is presented for better spatial resolution and measurement range.
KEYWORDS: Dispersion, Microwave radiation, Telecommunications, Signal processing, Digital signal processing, Signal detection, Sensors, Transmitters, Fiber optic communications, Optical amplifiers
A feasible and cost-effective online chromatic dispersion (CD) monitoring scheme for high speed optical communication system is demonstrated in this paper. Based on the formerly verified theoretical model, the output electrical power of a specific frequency band is tested to reflect the residual chromatic dispersion online. Thus the microwave devices are selected to form the electrical power detecting circuit, which consists of a PIN photodiode, a microwave power filter and a power detector in tandem. In the experiments, frequency band center were chosen at 5 GHz for the 10 Gbit/s system and 12 GHz for the 40 Gbit/s system. Then the output voltage of the detector was processed and converted to digital signal and the signal was processed to obtain the amount of the chromatic dispersion of the tested systems. For the 40 Gbit/s system, the maximum detectable chromatic dispersion was around 130-ps/nm and a resolution of 5-ps/nm/db was achieved at the chosen frequency band centered at 12 GHz. Performance of the microwave devices and comparison of the experimental results at different frequency bands are also discussed, which verified that the chosen center frequency was suitable for detection of CD in optical communication system beyong 10 Gbit/s speed.
A white light Michelson interferometer is designed to measure the distributed polarization mode coupling in High birefringence polarization-maintaining fibers (HiBi-PMFs). Using a Michelson interferometer to compensate the optical path difference induced by the modal birefringence of PMF, both power coupling intensity and position of the coupling point can be acquired. Traditionally, this technique requires only one polarization mode in the PMF to be exited or both polarization modes to be exited with equal intensity. This needs precise alignment of the polarization direction with the principal axis of the PMF. In practice, it's not easy to realize. In this paper, the influence of the incident polarization extinction ratio (PER) on the measurement result was evaluated theoretically and experimentally. A polarization state adjusting mechanism is designed. An analyzer can be oriented at any angle of the PMF's principle axes. By alternating this angle between 0o, 90o and 45o, the incident PER can be calculated and the measurement can be carried out with random exited polarization mode. An instrument was designed and implemented to verify this scheme. Spatial resolution better than 7cm and coupling strength sensitivity less than -75dB are realized.
A vertical-shaft-type Mirau white-light phase-shifting interferometer is designed based on white-light phase-shifting interference microscopy in this paper. The interferometer is composed of an illumination and interference imaging part, a piezoelectric transducer in the vertical direction, a two-dimensional scanning part in the test surface, image collection and interferograms analysis part. The light illuminates the sample and the test surface uniformly, and the interferogram is formed. In order to get phase-shifting, the move of the objective is driven by PZT. The three-dimensional scanning system consists of a two-dimensional horizontal motorized stage and a vertical piezoelectric transducer. Multi-aperture stitching extends the measurement range in the test surface. A new pixel divided phase-extracting algorithm was put forward in combination with a residues-pretreatment phase-unwrapping algorithm based on image segmentation. The algorithm is used to minimize the phase-shifting error and nonlinearity error of the detector. The surface profile of a fiber connector with fiber inserted was measured. Mean value of the protrusion between fiber and fiber connector was measured to be 45.7nm, with 0.9 nm error. The mean height of a spot on the end surface of fiber connector was measured to be 23.6nm, with 0.7nm error.
A multichannel bidirectional dynamic data transmission system (DDTS) through a rotary interface with one fiber is designed based on a fabricated single pass fiber optic rotary joint. The feasibility of transmission system is tested at both 1310- and 1550-nm wavelength bands. The performance of this DDTS was measured using optical spectrum analyzer and lightwave multimeter. The insertion losses of DDTS were 1.55 and 1.20 dB at 1310- and 1550-nm wavelength bands, respectively. The total bandwidth of the DDTS is more than 170 nm.
An 8-channel switching node with routing function is designed in this paper using a high-performance digital cross-point switch. The throughput of the 8-channel routing node is 10 Gbit/s. Combined with time division multiplexing (TDM) technique, a high-speed optical interconnection network was designed. Using Optical Network Interface Cards (ONIC) and the designed routing node, a two-layer optical interconnection network with structure of ring and star topology is designed. Based on circuits cascading technique, the network can be expanded to meet the request of large scale data communication with low communication latency.
The numerical aperture (NA) of the double beam interferometers (DBI) can affect the accurate measurement of surface profiles. Based on the double beam interference microscope imaging theory, the fringe spacing will vary wide nonlinearly with the increasing of numerical aperture. The double beam interferometers require oblique incidence illumination, including Michelson, Mirau and Linnik types. The intensity distribution of the illumination across its stop is constant so the correction factor depends mainly on the NA in the Michelson and Linnik interferometers. The correction factor expression is derived in the Michelson interferometer. The reference surface is a central obscuration in the beam, which will reduce the effective numerical aperture in the Mirau interferometer. At the same numerical aperture, larger central obscuration has a much effect on the correction factor. The correction factor expression is determined by considering the influence of central obscuration and oblique incidence in the Mirau interferometer.
A microstructure inspection endoscope, based on directly imaging, is proposed. It is designed for detecting defects on the surface of optical fiber end. It is matched with FC or SC female fiber connector. The inspection head of the endoscope can be put into a 2.5-millimeter-diameter micro-pore. Its numerical aperture is not restricted by tiny dimension of object lenses. System resolution is increased to 600 line-pairs per millimeter. The endoscope consists of object lenses, scanner slab and kohler illumination system. The design provides possibility of various utilities such as aiming at a smaller subject by micro optical scanner and modeling the surface by tri-dimensional vision. And the optical system includes low-magnification lenses and high-magnification zoom lenses. Rough observation at low-magnification and particularly inspection at high-magnification are provided. The instrument has the advantages of high identification, compact configuration and flexible manipulation.
Both hardware and software are optimized simultaneously to improve the bus throughput of node computer in cluster computing network. A cost effective optical interconnection ring network is established using off-the-shelf PCs with windows operating system. A network adapter card ONIC is developed. Using ETDM and field program technique, the full bandwidth of the 32bit×33MHz PCI bus is reached in physical layer. In order to overcome the hardware and software data bottlenecks induced by using of general purpose platform such as PCs and Windows 2000 system, several methods are adopted to maximum the bus throughput of node computer. A user-level interface is designed to blur the kernel/user mode boundary of the software system, and bypass the OS overhead. Zero-copy DMA is realized. The bandwidth in application level using PIO and DMA transfer mode is improved 17 and 26 times respectively. The sustained bandwidth in application layer can reach 437.6Mbit/s. It’s also shown theoretically and experimentally that the selection of main board chipset, using memory space map, reasonable using of PIO and DMA transfer mode, using polling and large MTU will also improve the bus throughput of node computer considerably.
This paper deals with the problem that a great number of rotary joints are suffering the conflict between high efficiency of signal dynamic coupling and low requirement of precision mechanism. As a solution, a specific design of the infrared spatial interconnection rotary joint is presented accompanying with the discussion of requirements for the mechanism and the circuit. Benefit from infrared data interconnection between the stator and the rotor, the security of data transfer is ensured and the off-axis angle can vary from 0º to 30º, which contribute to a simpler mechanism and a compact rotary joint. Relative experiment shows that with this rotary joint, signals can be transmit securely, and the efficient data transmission speed is up to 1.4Mbps under Windows 2000 circumstance.
In this paper, a white light interferometer has been designed to measure the distributed polarization coupling in high birefringence fibers. The limitations to the measurement accuracy have been analyzed. The main structure is a Michelson interferometer. A superluminescent diode (SLD) has been adopted as the broadband source in the white light interferometer. Corner mirrors have been adopted to reflect the light beams in both arms of the Michelson interferometer. To enlarge the measurement range, the light beam in the scanning arm of the Michelson interferometer is reflected three times. Thus the scanning range of the interferometer is doubled for a certain linear motion rail. The full width half maximum (FWHM) spectrum of the SLD is 50 nm, and its central wavelength is 1300 nm. If the modal birefringence of the HBF is 6 X 10-4, a spatial resolution of 56 mm can be achieved. A high sensitivity photo detector and a high-resolution analog to digital converter (ADC) have been adopted. These devices are capable of testing a coupling point with accuracy up to -80 dB.
White light interferometry has been adopted to measure the distributed polarization coupling in high birefringence fibers. A superluminescent diode is adopted as the optical source in the white light interferometer. To enlarge the measurement range, the light beam in the scanning arm of the Michelson interferometer is reflected three times. Thus the scanning range of the interferometer is doubled. The full-width half-maximum spectrum of the SLD is 50 nm, and the central wavelength is 1300 nm. If the modal birefringence of the HBF is 5×10-4, a spatial resolution of 70 mm can be achieved. A high sensitivity photo detector and a high-resolution analog to digital converter have been adopted. The polarization coupling intensity measurement accuracy can be up to -75 dB.
In this paper, a novel method to measure the distributed polarization mode coupling in polarization-maintaining (PM) fibers is introduced. The measurement system is based on white light interference. A super luminescent diode is used as the broadband light source in the system. The whole test system is working on 1300nm wavelength. There are two main parts of the measurement equipment: polarization adjustment and a scanned Michelson interferometer. In order to improve the accuracy, a piezoelectric transducer (PZT) is applied in the scanned Michelson interferometer. The maximum length of tested polarization-maintaining fiber is one kilometer, and the spatial resolution of this method reached 60 mm along the tested PM fiber. The degree of polarization mode coupling that could be detected is —75dB.
We present a new device for determining the state of polarization (SOP) during the measurement of spatial distribution of mode coupling in high birefringent. polarization-maintaining (PM) fibers. The linear polarization light can be randomly rotate to obtain the best experimental result through it. And we draw a conclusion that in the distributed polarization coupling analyzer (DPCA) the fringe contrast is equal to 0.943 when the amplitude ratio is equal to 1. It can be widely used in the PM fiber testing and linearly polarized light interference system.
In this paper, an apparatus has been designed to inspect the end surface of fiber optic connectors. A white-light high-brightness light emitting diode has been adopted to offer enough light power. Zoom lenses comprise field lens and achromatic lens with a large range of magnification from 1.25 to 60. They can be used to inspect not only the whole ferrule but also the details of the core. The illumination system has two modes: perpendicular and oblique. In oblique illumination, the relation on the maximum length of shadow
along the incident direction and the angle of oblique illumination is disclosed and the curvature of shadow is drawn. Fiber undercut and protrusion can be judged whether they are satisfied the tolerance with the curvature.
A noncontact system for detecting and monitoring the grain and contour of optical connector end face based on Mirau-type interferometer is proposed in this paper. In this system, phase shift technique has been adopted. A five steps algorithm is presented. By this algorithm, the computer can analyze the interference pattern and unwrapped the phase information of the detected surface. Then we can get the differential height of every point on the surface. This
method is capable of measuring fiber height to ±0.003 microns and radius of curvature and offset of polish to ±0.30 mm and ±2.0 microns respectively. So we can get not only 2-D and 3-D topography of testing surface, but also the evaluation parameters of surface roughness.
In this paper, we overview the research and development of optical interconnection network from 1993 to 2001 in Tianjin University. These works are divided into two categories. One is optical interconnection network for massively parallel processing systems. Another is optical interconnection technique for computer clusters. In the former, we have designed a massively parallel processing system that consists of 64 processors, which are interconnected by optical fiber links. In the later, we have developed giga-bitls optical links, hardware-routing optical rings and wavelength-routing dual rings. The optical layer data transmission speed has been improved from 20 Mbit/s in the massively parallel processing system to 1.25 Gbit/s in the computer clusters. Meanwhile, the communication latency has been reduced to 200 ns adopting hardware-routing technique. To further reduce the data packet routing-latency, wavelength routing technique has been implemented in a dual-wavelength ring. Finally, we have designed some novel network structures for tera-bit/s optical interconnection network.
A multi-pipeline optical interconnection network for distributed computing system has been designed. Each sub-layer network is connected to the ring with an access node (AN), which can transmit data at every wavelength with a tunable laser diode. The data transmission speed at each wavelength is 1.25 Gbit/s. With 8 wavelengths, a total bandwidth of 10 Gbit/s can be obtained. Each AN only receives a certain wavelength. With a band pass filter, the desired optical signal can be dropped down. Pipelining data transmission is achieved among different wavelengths. This network is a multi-pipeline structure. So the communication latency and communication overheads can be decreased. Meanwhile, the ring topology has good scalability. The scale of the network can be expanded adopting more wavelengths at each access node.
A high-performance metropolitan area network has been designed with the combination of coarse wavelength division multiplexing (CWDM) and electrical time division multiplexing (ETDM) techniques. The network consists of n access nodes with each node transmitting and receiving m wavelengths. Virtual multi-channel (VMC) has been achieved at each wavelength via ETDM technique to minimize the data blocking possibility. This network structure has high bandwidth, low communication latency and high performance-to-cost ratio. A prototype network of 6 access nodes has been implemented with 4 virtual channels at each wavelength. The data transmission speed at each wavelength is 1.25 Gbit/s. It can be upgraded to 2.5 Gbit/s. The network has high flexibility and scalability. To further expand the network capacity, multi-wavelength window CWDM technique can be adopted at 1300 nm and 1550 nm simultaneously.
This paper presented an optical interconnection multiple PC system connected by a ring network. This multiple PC system uses Linux Operating system, and the standard communication protocol of complying with Ethernet specification. This paper studied the factors that influence the interconnection performance among multiple computers, including the effect of the buffer size of OLI on the bandwidth of network layer, and the effect of retransmission method on the performance. The results of ping-pong test show that optical fiber link is able to provide high-bandwidth and low-latency communication for a multi-PCs system. We found that the performance of the interconnection network can be improved by improving the interface match between the optical fiber link and computer bus input/output. Besides, the development of a chip to implement network interface and a part of network protocol, such as developing with FPGA device in this paper, could result in the higher performance of the interconnection.
KEYWORDS: Data transmission, Field programmable gate arrays, Clocks, Human-machine interfaces, Data communications, Interfaces, Local area networks, Switching, Computer networks, Time division multiplexing
A giga-bit per second optical ring has been designed. The data link layer bandwidth of the network is 1.5 Gbit/s. Hardware routing has been achieved by field programmable gate array (FPGA) to minimize the communication latency. As a result, the point-to-point communication latency between adjacent node computers is less than 300 ns. To reduce the data communication latency and have a more efficient usage of the data link layer bandwidth, virtual multi-channel transmission mechanism has been achieved with hardware. The network supports a maximum of four virtual channels for each physical data link. Time slots can be dynamically assigned to each virtual channel. The length of each time slot can also be dynamically selected based on the length of each data packets. Zero wait time has been achieved for the switching between different virtual channels. The relationship between the network performance and the number of virtual channels has also been analyzed in this paper.
In this paper, high-density and large-capacity parallel data reliable transmission has been accomplished in high electro-magnetic interference environments via virtual- parallel optical transmission technique. Through time division multiplexing (TDM), all the parallel data signals and control signals are converted to high-speed serial data stream. Each bit is transmitted in a time slot during a frame period Thus, the parallel signals can be transmitted using only one opto-electronic device. Each optical transmission channel consists of two optical fibers, can achieve full-duplex transmission of 24 bits parallel signals. The maximum frame rate is 75 MHz. This data transmission card can be expanded to 6 channels, has a maximum data throughput of 15 Gbps. This optical data transmission link can work properly for a wide range of supply voltage. When the supply power voltage varied from 4.2 to 7.0 volts, the bit error rate (BER) is still below 10E-12.
In this paper, a communication protocol has been designed for the two-layer scalable optical interconnection network (TSOINet) designed in Tianjin University. The communication protocol has been designed based on TCP/IP (transmission control protocol/internet protocol) protocol. But it is more efficient than TCP/IP for data transmission in TSOINet. An auxiliary channel has been introduced in TSOINet for transmission of the communication status messages among the sub-layer rings. Many network management functions, such as flow control, hand shaking, etc., can be achieved via the auxiliary channel, so the communication overheads can be decreased. The performance of the communication protocol has been evaluated compared to TCP/IP protocol for data transmission in TSOINet.
In this paper, some study results to apply fiber link to a computer cluster are presented. The research is based on a ring network topology for a cluster system, which is connected by gigabit/s virtual parallel optical fiber link (VPOFLink) and its driver is for Linux Operating System, the transmission protocol of VPOFLink is compliant with Ethernet standard. We have studied the effect of different types of motherboard on transmission rate of the VPOFLink, and have analyzed the influence of optical interconnection network topology and computer networks protocol on the performance of this optical interconnection computer cluster. The round-trip transmission bandwidth of the VPOFLink have been tested, and the factors that limit transmission bandwidth, such as modes of forwarding data packets in the optical interconnection ring networks, and the size of the link buffer etc., are investigated.
In this paper, we present a low cost fiber-optic data link for the computing cluster. The link is a 32 bit-virtual- channel fiber-optic computer bus used only a pair of OE devices and fibers. The link is integrated with the popular PCI Bus interface in order to make the link hold the same bandwidth as that of the PCI Bus, and it can operate under managed by PCI Bus. Our research addresses how to match accessing bandwidth between computer bus and high-speed optical interconnections, and how to make low overhead and latency interfaces between optics and electronics, and integrates fiber optic link into computing system designs.
In this paper, wavelength routing technology is applied to computer interconnection network. By analyzing the relationship between wavelength and networks routing, we describe a concept of wavelength being used as network address, and propose a wavelength routing topology to extend the scale of networks and realize scalability of networks. A twin-wavelength ring network to implement and test the function of wavelength routing is presented, and the main units of the twin-wavelength ring network are presented as well. In addition, we put forward tow methods to implement it. The design method of physical link driver software for Linux, which uses optical interconnection interface as network interface for parallel computing, is also introduced.
This paper describes the two-layer scalable wavelength routing optical interconnection network being developed in Tianjin University. The top layer of the network is multi- wavelength bi-directional optical bus, which has high bandwidth and low latency. The optical bus is made up of passive components, no wavelength-tunable devices have been sued. As a result, the optical bus has low communication latency that is mainly decided by the optical fiber length. The sub-layer of the network is single-wavelength ring, which has low communication latency and high-scalability. In each ring, a wavelength routing node is used for data transmission between the ring and the optical bus. Each node computer is connected to the ring using an optical network interface card, which is based on peripheral component interconnect bus. The communication latency inside the ring is decreased using synchronous pipelining transmission technique. The scale of the ring is mainly limited by the efficient bandwidth required by each node computer. The number of rings is mainly decided by the optical power of the laser diodes and the sensitivity of the optical detectors. If Erbium doped fiber amplifier is used in the optical bus, the scale of the network can be further developed.
It is well known that a wavelength can be regarded as an address code of a packet in the optical interconnection network. In our scheme, we use wavelength as a part of an address to build a multiple wavelengths optical interconnection ring network. The network consists of double layer rings, the routing inside a ring is electronic, and wavelength routing technology is applied to switch between rings. Two wavelength are used in the network, one is for transmitting data inside local ring, another is for switching to another ring. The detail of the network is described in this paper. Besides, a low-cost virtual parallel optical link and optical interconnection interface, which is bound up with the multiple-wavelengths network, is presented.
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