Gigabyte/s parallel fiber-optic links based on edge emitting laserdiode arrays

We present a ten-channel parallel fiber optic link consisting of a transmitter based on an edge emitting laser diode array operating nominally at 1 μm wavelength and a complementary receiver based on an InGaAs pin photodetector array. We demonstrate fiber optic link performance up to data rates of 1 Gb/s per channel with low skew at measurement time limited bit error rates lower than 10^-11 over 100 m of multimode fiber ribbon cable. The transmitter is operational, with very clear eye opening, up to baseplate temperatures of 105°C     

Multimode Fiber as Random Code Generator— Application to Massively Parallel MIMO Transmission

We propose a novel multiple-input multiple-output (MIMO) scheme over multimode fiber, acting as a distributed random code generator fed by spatial codes, using silicon photonics in the transmitter and maximum-likelihood (ML) electronic detection in the receiver, providing an alternative to coarse wavelength division multiplexing (CWDM) for implementation of ultrahigh speed parallel transmission over short-range optical interconnects. The optical MIMO system utilizes mutually coherent transmission and conventional direct detection with one-bit quantization, facilitating cost-effective application to 100 Gb/s links over < 50 m.     

Technology development of a high-density 32-channel 16-Gb/s opticaldata link for optical interconnection applications for theoptoelectronic technology consortium (OETC)

A parallel, 32-channel, high density (140 μm pitch), 500 Mb/s NRZ, point-to-point, optical data link has been fabricated using existing GaAs IC, silicon optical bench (SiOB), and multichip module (MCM-D) technologies. The main components of the transmitter and the receiver modules are a GaAs-based vertical cavity surface emitting laser (VCSEL) array at 850 mn with its IC driver array chip and an integrated metal-semiconductor-metal (MSM) receiver (photodetector and signal processing circuits) array at 850 nm. The package module uses a modified 164 I/O JEDEC premolded plastic quad flat pack (PQFP) in combination with a polymer film integrated circuit (POLYFIC) chip carrier. The electrical input and output are 500 Mb/s NRZ binary signals. The optical I/O in both modules consists of a directly-connectorized (nonpigtail) fiber array block that plugs into the 32×1 optical fiber ribbon directly on one side and accepts 32 optical signals from the SEL array or delivers them to the MSM receiver array via a gold-coated 45° polished fiber array mirror. The MACII-32 ribbon cable is an enhanced version of the standard MACII connector ribbon cable. This paper characterizes key components of the optical data link, describes its package design, and discusses preliminary component and optical data link test results     

Parallel-optical interconnects >100 gb/s

A parallel-optical interconnect with 12 channels operating at 8.5 Gb/s giving an aggregate data rate of 102 Gb/s is demonstrated, to the authors' knowledge, for the first time. The paper describes and demonstrates 13 /spl times/ 16-mm cross-section 12-channel parallel-optic transmitter and receiver modules with each channel operating at a data rate of 8.5-10 Gb/s. This was achieved using bottom-emitting 990-nm vertical-cavity surface-emitting lasers and bottom-illuminated InGaAs-InP photodetectors flip-chip bonded directly to 12-channel transmitter and receiver integrated circuits, respectively. In addition, 102-Gb/s link results are demonstrated over 100 m of 50-/spl mu/m-core standard multimode ribbon fiber. A bit-error ratio of <10/sup -13/ was measured on a single channel after transmission through 100 m of multimode fiber at a data rate of 8.5 Gb/s with all 12 channels operating simultaneously.     

A quaternary partial-response class-IV transceiver for 125 Mbit/sdata transmission over unshielded twisted-pair cables: principles ofoperation and VLSI realization

The paper describes an experimental transceiver for full-duplex transmission at a rate of 125 Mbit/s over unshielded twisted-pair cables of ordinary voice-grade quality, intended for use in a fiber distributed data interface (FDDI) network. Quaternary partial-response class-IV (QPRIV) overall-channel signaling with near-end crosstalk (NEXT) cancellation and maximum-likelihood sequence detection is employed. The spectral shape of the QPRIV signals facilitates equalization and achieving compliance with EMC regulations. Since in an FDDI system each transmitter can be clocked independently, the receiver must cope with phase drift between NEXT signals to be cancelled and signals received from the remote transmitter. With the chosen transceiver architecture, digital-to-analog conversion of transmit signals, analog-to-digital conversion of receive signals, and adaptive NEXT cancellation are performed synchronously with the transmitter clock. The rate change from transmit timing to controlled receive timing is accomplished by an adaptive equalizer in conjunction with an elastic buffer and occasional coefficient shifts. The equalizer is adjusted rapidly enough to allow for a maximal phase drift of ±100 ppm. The implementation of all digital signal-processing functions in a single 0.5 μm CMOS VLSI prototype chip is discussed. The employed standard-cell design resulted in a power consumption of 6 W. Significantly lower power consumption can be achieved by custom design of highly repetitive processing elements     

140 Mbit/s receiver performance at 2.4 μm using InAsSbP detector

A 140 Mbit/s optical receiver has been demonstrated using for the first time an InAsSbP photodetector operating at room temperature and optimised for operation at 2.4 μm, close to the minimum-loss wavelength of fluoride fibre. The receiver sensitivity was measured to be -32 dBm at 140 Mbit/s and 2.4 μm     

120-Gb/s VCSEL-based parallel-optical interconnect and custom 120-Gb/s testing station

A 120-Gb/s optical link (12 channels at 10 Gb/s/ch for both a transmitter and a receiver) has been demonstrated. The link operated at a bit-error rate of less than 10/sup -12/ with all channels operating and with a total fiber length of 316 m, which comprises 300 m of next-generation (OM-3) multimode fiber (MMF) plus 16 m of standard-grade MMF. This is the first time that a parallel link with this bandwidth at this per-channel rate has ever been demonstrated. For the transmitter, an SiGe laser driver was combined with a GaAs vertical-cavity surface-emitting laser (VCSEL) array. For the receiver, the signal from a GaAs photodiode array was amplified by a 12-channel SiGe receiver integrated circuit. Key to the demonstration were several custom testing tools, most notably a 12-channel pattern generator. The package is very similar to the commercial parallel modules that are available today, but the per-channel bit rate is three times higher than that for the commercial modules. The new modules demonstrate the possibility of extending the parallel-optical module technology that is available today into a distance-bandwidth product regime that is unattainable for copper cables.     

Proton implanted VCSEL's for 3 Gb/s data links

Transverse single-mode and multimode intensity modulated butt-coupled InGaAs vertical cavity surface emitting lasers (VCSEL)s are investigated as a light source for optical fiber communication systems. Data transmission at 3 Gb/s with a bit error rate (BER) of less than 10 ^-11 is reported for both 4.3 km of standard fiber, as well as 0.5 km of multimode graded-index fiber, 10-μm active diameter single-mode VCSELs are shown to have lower mode competition noise requiring 3 dB and 6 dB less power at the front end receiver at a BER of 10^-11 compared to 19-μm and 50-μm active diameter devices, respectively. In data transmission with multimode VCSELs, the dispersion penalty is lower than for single-mode sources since the noise at the receiver is mainly determined by transmitter-mode competition noise     

Frequency stabilized 622-Mb/s 16-channel optical FDM system and itsperformance in 1.3/1.55-μm zero-dispersion fiber transmission

A study has been conducted on a densely multiplexed 16-channel optical FDM system. A transmitter contains 16 two-section MQW DFB-LD's and a star coupler. An automatic optical multi-frequency controller stabilizes each LD of 10 GHz spacing within ±100-MHz accuracy. A receiver consists of heterodyne-delay-demodulators using a polarization diversity. Any desired channel can be tuned by a novel frequency discriminator with no insensitive frequency region. The system has successfully transmitted 622 Mb/s-16-channel HDTV signals through 110 km long 1.3 μm-zero-dispersion fiber. We have also studied error rate degradation due to four-wave mixing in a 1.55 μm-dispersion-shifted-fiber. Experimental results have revealed the allowable total input power to be +2 dBm for dispersion-shifted fibers     

1.5-μm-band optical time domain reflectometer for single-modeoptical fiber using a P2O5-highly-doped fiberRaman laser

A wide-dynamic-range 1.5-μm-band optical time-domain reflectometer (OTDR) for single-mode optical fibers using a P₂O₅-highly-doped fiber Raman laser light source and a cooled Ge-p-i-n photodiode is realized for the first time. The stimulated-Raman-scattering properties of P₂O₅-doped single-mode fiber are investigated. Using this fiber and an Nd:YAG laser operating at 1.32 μm, a high-power light pulse at 1.59 μm is generated with high efficiency. Using the stimulated-Raman-scattering light as the light source and a high-sensitivity optical receiver, a 1.5-μm-band OTDR having a one-way dynamic range of 35 dB is realized     

A silicon-based moving-mirror optical switch

A multimode 2×2 optical switch made from chemically micro-machined silicon piece parts is described. This switch uses microlenses, aligned to fibers by a silicon base, to expand the optical beam and relax alignment tolerances and a pivoting silicon mirrors as the switching mechanism. The moving mirror switch meets or exceeds all the requirements for FDDI applications. The switch loss is typically 0.7 dB and operates at 5 V and 30 mA. The switch insertion/deinsertion time is less than 10 ms, and the optical interruption time is less than 1 ms. The switch design, which minimizes alignments in fabrication and provides for z-axis assembly and the low cost of the high precision piece parts contribute to making this a low-cost switch to manufacture     

140Mb/s混合集成光发射机

研制了一种混合集成140Mb/s单模半导体激光器发射机。该发射机由高速缓冲整形放大、LD驱动功能模块、LDAPC——LD自动功率控制功能模块、LDATC——LD自动温度控制功能模块,LD保护及寿命,信号终断告警功能模块和调顶功能模块所构成。发射机调制出纤光功率为-6dBm～-3dBm、消光比≤10％,在0～45℃范围内光功率变化在±1dB以内。该发射机和本所同时研制的混合集成光接收机配套,构成了目前140Mb/sPCM数字光端机的全新产品。     

2.24-Gbit/s 151-km optical transmission system using high-speedintegrated silicon circuits

Optical transmission experiments performed at 2.24 Gb/s using standard single-mode fiber with dispersion zero at 1.3 μm are discussed. In the optical transmitter, a 1.5-μm-wavelength distributed feedback laser is directly modulated by means of a special electrical drive pulse shaping technique. A link length of up to 151 km is bridged. This is the longest repeater distance at 2 Gb/s using direct detection without optical amplifiers reported so far. Moreover, the transmission system includes multiplexing and demultiplexing equipment using specially developed high-speed silicon integrated circuits. The whole system is assembled in a version suitable for field trial applications     

A Low‐Crosstalk Design of 1.25 Gbps Optical Triplexer Module for FTTH Systems

In this paper, we analyzed and measured the electrical crosstalk characteristics of a 1.25 Gbps triplexer module for Ethernet passive optical networks to realize fiber‐to‐the‐home services. Electrical crosstalk characteristic of the 1.25 Gbps optical triplexer module on a resistive silicon substrate should be more serious than on a dielectric substrate. Consequently, using the finite element method, we analyze the electrical crosstalk phenomena and propose a silicon substrate structure with a dummy ground line that is the simplest low‐crosstalk layout configuration in the 1.25 Gbps optical triplexer module. The triplexer module consists of a laser diode as a transmitter, a digital photodetector as a digital data receiver, and an analog photodetector as a cable television signal receiver. According to IEEE 802.3ah and ITU‐T G.983.3, the digital receiver and analog receiver sensitivities have to meet ‐24 dBm at BER=10^?12 and ‐7.7 dBm at 44 dB SNR. The electrical crosstalk levels have to maintain less than ‐86 dB from DC to 3 GHz. From analysis and measurement results, the proposed silicon substrate structure that contains the dummy line with 100 μm space from the signal lines and 4 mm separations among the devices satisfies the electrical crosstalk level compared to a simple structure. This proposed structure can be easily implemented with design convenience and greatly reduce the silicon substrate size by about 50 %.     

Integrated 460 GHz photonic transmitter module

A photonic sub-millimetre (sub-mm) wave transmitter module has been developed and fabricated. The module consists of a 1.55 μm waveguide InP photodetector monolithically integrated with a planar full wave slot antenna and passive lowpass filter for DC bias supply. For the first time, optical heterodyne 460 GHz sub-mm signal generation is demonstrated It is further shown that the module can effectively replace the classical solid-state oscillator of an astronomical superconductor-insulator-superconductor heterodyne receiver The module generates sufficient sub-mm wave power to operate the receiver under optimum conditions     

Assessment of radiation-induced loss for AT&T fiber-optictransmission systems in the terrestrial environment

Environmental radiation dose rate estimates are provided for both outdoor terrestrial and indoor environments. Laboratory radiation sensitivity measurements are reported for the AT&T standard single-mode fiber and standard and radiation-hardened multimode fibers. These are used to estimate typical system losses for long-haul, trunk, feeder, local area network, and optical data environments. It is reported that radiation-induced loss is unusually harsh environments can be minimized by using the radiation hardened 62.5/125-μm multimode fiber, which has sensitivities roughly an order of magnitude lower than the standard product at 0.85 μm and almost two orders of magnitude lower at 1.3 μm     

PCB-compatible optical interconnection using 45/spl deg/-ended connection rods and via-holed waveguides

In this paper, a new architecture for a chip-to-chip optical interconnection system is demonstrated that can be applied in a waveguide-embedded optical printed circuit board (PCB). The experiment used 45/spl deg/-ended optical connection rods as a medium to guide light paths perpendicularly between vertical-cavity surface-emitting lasers (VCSELs), or photodiodes (PDs) and a waveguide. A polymer film of multimode waveguides with cores of 100/spl times/65 /spl mu/m was sandwiched between conventional PCBs. Via holes were made with a diameter of about 140 /spl mu/m by CO/sub 2/-laser drilling through the PCB and the waveguide. Optical connection rods were made of a multimode silica fiber ribbon segment with a core diameter of 62.5 and 100 /spl mu/m. One end of the fiber segment was cut 45/spl deg/ and the other end 90/spl deg/ by a mechanical polishing method. These fiber rods were inserted into the via holes formed in the PCB, adjusting the insertion depth to locate the 45/spl deg/ end of rods near the waveguide cores. From this interconnection system, a total coupling efficiency of about -8 dB was achieved between VCSELs and PDs through connection rods and a 2.5 Gb/s /spl times/ 12-ch data link demonstrated through waveguides with a channel pitch of 250 /spl mu/m in the optical PCB.     

Bragg gratings in multimode and few-mode optical fibers

Bragg gratings in optical fibers in multimode propagation are investigated experimentally and theoretically. Bragg gratings formed in optical fibers in multimode propagation show multiple reflection peaks or multiple transmission dips in the reflection or transmission spectra, respectively. For standard graded-index multimode fiber, the number of reflection peaks of a Bragg grating depends on excitation condition of propagating modes. The number of reflection peaks of a Bragg grating at around 1.55 μm is 19 for highly multimode excitation and 3-4 for lower order mode excitation. We analyze the phase-matching conditions of the propagating modes and identify half of the reflection peaks as the reflection to the same mode and the rest as the reflection to the neighboring modes. In dispersion-shifted fiber, a Bragg grating at around 0.8 μm in three-mode propagation shows three reflection peaks in the reflection spectrum. The temperature dependence of each reflection peak is similar to that of a conventional Bragg grating in single-mode fiber. Polarization dependence measured on a Bragg grating in multimode graded-index fiber is negligible. An advantage of Bragg gratings in multimode fiber (MMF) and the applications are discussed     

Wide bandwidth low noise pinFET receiver for high-bit-rate opticalpreamplifier applications

A wide bandwidth low noise pinFET receiver has been fabricated and characterised for optical preamplifier applications. The receiver uses a low capacitance planar pin diode as the photodetector. A bandwidth of 7.08 GHz was measured. The measured input noise current for the receiver front-end is lower than 12 pA/√(f). Using a 1.3 μm DFB laser as the transmitter, at a data rate of 4 Gbit/s, the measured receiver sensitivity is -25.5 dBm with a bit-error-rate of 1×10 ^-9. A set of two of such receivers has also been tested in a 1.3 μm polarisation-insensitive optical preamplifier system experiment. The measured receiver sensitivity, including an optical insertion loss of 1.5 dB, is -29.3 dBm     

A passive star-configured optical local area network using carrier sense multiple access with a novel collision detector

This work describes design and theoretical performance of a passive star-configured multimode optical fiber local area network that employs carrier sense multiple access with collision detection (CSMA/CD). We introduce a novel collision detection method that uses collision sequences constructed from cyclic error-correcting codes and a sequence weight violation rule. Each transmitter has its own unique sequence and all sequences have identical Hamming weight. The collision detection sequence is inserted in each packet header. Our method enables detection of collisions subject to a wider dynamic range variation than competing methods proposed up to now and is extremely simple. The collision detector consists of a counter which estimates the Hamming weight of the received collision detection sequence. It works both for non-return-to-zero and Manchester coding. The collision detector is analyzed for an avalanche photodiode receiver. The general performance analysis is done both with Gaussian approximations and with method of moments. A dynamic range of 17 dB seems possible for a transmitter with an extinction ratio of 100 and a simple receiver with a fixed threshold. An explicit table of 56 collision detection sequences based on the Golay code is presented.