Showing papers on "Wavelength-division multiplexing published in 1991"
TL;DR: In this paper, it was shown that solitons of different velocities are transparent to each other in a system using lumped amplifiers, as long as the length of the collision is long enough relative to the spacing between amplifiers or a possibly longer period of variation in some other parameter, such as the fiber's chromatic dispersion.
Abstract: One attractive feature of the all-optical approach to ultra long-distance transmission is that it greatly facilitates wavelength division multiplexing (WDM). It is known that solitons of different velocities are transparent to each other. It is shown, through numerical simulation, that such transparency is also maintained in a system using lumped amplifiers, as long as the length of the collision (the distance the solitons travel down the fiber while passing through each other), is long enough relative to the spacing between amplifiers, or to a possibly longer period of variation in some other parameter, such as the fiber's chromatic dispersion. This result implies the potential for at least several multigigabits-per-second WDM channels spanning just 1 or 2 nm, in a system of transoceanic length (7000-9000 km). >
262 citations
Patent•
05 Apr 1991
TL;DR: In this paper, the authors proposed a multichannel optical multi-channel data communication link consisting of a multimode laser diode source connected to the transmitter, a device for modulating the source with each channel of data to generate a modulated light wave, and a wavelength division multiplexing device at the transmitter.
Abstract: An optical multi-channel data communication link transmits data from a transmitter to a remote receiver. The link includes a multimode laser diode source connected to the transmitter, a device for modulating the source with each channel of data to generate a modulated light wave, and a wavelength division multiplexing device at the transmitter. The wavelength division multiplexing device has paraxial optics for multiplexing the light waves to produce a multiplexed signal. Multimode fiber optic means are connected to the multiplexer and pass the multiplexed signal to the remote receiver. A wavelength division multiplexer has paraxial optics for demultiplexing the multiplexed signals at the receiver to produce demultiplexed light waves. Each of the demultiplexed light waves are converted for use by the receiver. Preferably, each of the wavelength division multiplexer and demultiplexer has a littrow reflecting grating and a lens which are paraxially aligned with the multimode fiber optic means to provide channel separation of less than 50 nm.
242 citations
TL;DR: In this paper, the effect of weak refractive-index nonlinearity of optical fibers on pulse shape was investigated using computer simulations of long-distance transmission and the analysis was confined to normal pulses and does not consider solitons.
Abstract: The effect of the weak refractive-index nonlinearity of optical fibers on pulse shape is investigated using computer simulations of long-distance transmission. Fiber losses are canceled by periodically spaced optical amplifiers whose spontaneous emission noise is, however, not included in the simulations. The analysis is confined to normal pulses and does not consider solitons. Several conclusions are drawn. (1) If wavelength division multiplexing (WDM) of two channels is used in a uniform fiber without dispersion fluctuations, catastrophic buildup of four-wave mixing occurs if one primary channel is located at the zero-dispersion wavelength. (2) If two pulses with different carrier frequencies collide in a uniform fiber with no gain or loss discontinuities, their four-wave mixing products reach a peak during complete pulse overlap, but this spurious power dies away as the pulses separate. (3) Two-channel WDM transmission of light modulated in amplitude-shift keying format appears feasible at 2.5 GB/s over distances of 7500 km. >
202 citations
TL;DR: In this article, a tunable signal gain equalization was demonstrated in three-stage Er/sup 3+/-doped fiber amplifiers using a waveguide type Mach-Zehnder (MZ) optical fiber.
Abstract: Tunable signal gain equalization is demonstrated in three-stage Er/sup 3+/-doped fiber amplifiers using a waveguide type Mach-Zehnder (MZ) optical fiber. A 29-channel multiplexed system is examined where signal wavelengths are positioned from 1.548 to 1.555 mu m. By adjusting the MZ transmittance with the external control current, tunable gain equalization is achieved at the output of each amplifier. >
194 citations
TL;DR: In this article, an optical notch filter was incorporated within the length of all erbium-doped fiber amplifier, which made it possible to enhance the amplifier gain at wavelengths around 1550 nm.
Abstract: An optical notch filter was incorporated within the length of all erbium-doped fiber amplifier. Careful choice of the filter characteristics and location made it possible to enhance the amplifier gain at wavelengths around 1550 nm. An amplifier with 27-dB gain and 33-nm bandwidth was demonstrated. The saturation characteristics of the amplifier were uniform across its gain spectrum, making it ideal for wavelength division multiplexed (WDM) application. >
157 citations
TL;DR: In this article, reflection gratings and out-coupling taps for sensors can be written holographically within the core of many commercial fibers available today, and the gratings appear to be permanent and have been tested to temperatures in excess of 500°C.
Abstract: Bragg reflection gratings and out-coupling taps for sensors can be written holographically within the core of many commercial fibers available today. The gratings appear to be permanent and have been tested to temperatures in excess of 500°C. Quasi-distributed temperature, strain, pressure, chemical, and interferometric sensors can be made with the wavelength selective, reflection gratings, and taps. The fiber gratings, and the different types of sensors they can make, conveniently lend themselves to (wavelength-division multiplexing) WDM, (time-division multiplexing) TDM, and (frequency-division multiplexing) FDM types of multiplexing schemes. Instrumentation to detect the multiple sensors and measure their spectral shift for localized and quasi-distributed sensing is currently under development.
142 citations
TL;DR: A study of integrated optic devices based on adiabatic principles is reported in this article, which includes a 3-dB coupler, a full coupler and an asymmetric Y-coupler for a 13-155- mu m-wavelength multiplexer.
Abstract: A study of integrated optic devices based on adiabatic principles is reported The components are a 3-dB coupler, a full coupler, a polarization splitter, a wavelength multiplexer, and two mode shape transformers All components were fabricated from doped silica and silicon nitride films on silicon substrates Results are given for an adiabatic full coupler and an adiabatic 3-dB coupler, an asymmetric Y-coupler for a 13-155- mu m-wavelength multiplexer, and a tapered waveguide for mode shape transformation >
135 citations
TL;DR: In this paper, the switching of a 20 Gbit/s pulse train at 2.5 Gbps was demonstrated in an all-fibre NOLM with a long loop (6.4 km) ensuring low power for the switching pulses.
Abstract: The switching of a 20 Gbit/s pulse train at 2.5 Gbit/s in an all-fibre NOLM is demonstrated. An entirely semiconductor case powered configuration was used with a long loop (6.4 km) ensuring low power (10 mW) for the switching pulses.
93 citations
07 Apr 1991
TL;DR: A wavelength division multiplexing transmissive star network is investigated, in which each node has one tunable transmitter with limited tuning capability and multiple fixed receivers and an efficient approximate analysis with drastically reduced computational complexity is presented.
Abstract: A wavelength division multiplexing (WDM) transmissive star network is investigated, in which each node has one tunable transmitter with limited tuning capability and multiple fixed receivers. Two synchronous channel access protocols requiring no pretransmission penalty are considered: random access and fixed transmission scheduling. An efficient approximate analysis with drastically reduced computational complexity is presented. In spite of the reduced complexity, the presented approach produces very accurate results and can serve in producing the most cost-effective system design for given performance requirements. >
90 citations
TL;DR: In this paper, a grating spectrograph in InGaAsP/InP suitable for use in the wavelength region from 1.2 to 1.6 μm is presented.
Abstract: A grating spectrograph in InGaAsP/InP suitable for use in the wavelength region from 1.2 to 1.6 μm is presented. Experiments for devices with a channel spacing of 3.7 nm and more than 30 channels between 1.48 and 1.59 μm are described. The measured cross talk level is below −25 dB. The devices have only very low polarization sensitivity. This spectrograph is suited for monolithic integration with photodiodes, laser diodes, or optical amplifiers on a single chip.
81 citations
TL;DR: In this paper, a visible, surface-emitting, solid-state diode laser for InGaAs, InP, and GaAs geometries, as well as for several other devices, is described and demonstrated.
Abstract: Proof-of-concept devices to create surface-emitting visible lasers are described and demonstrated. A visible, surface-emitting, solid-state diode laser for InGaAs, InP, and GaAs geometries, as well as for several other devices, is discussed. The use of a multilayer system to enhance the waveguide harmonic mixing over a large bandwidth is demonstrated. The resulting surface-emitted light can then be used to measure frequency differences of multiple optical channels in a fiber communication system. It can also be used for nonblocking switching systems. Since phase is preserved by the harmonic mixing, the device is also usable in coherent communication schemes. Experimental measurements of harmonic generation coefficients for a large Al alloy content in AlGaAs are presented. >
TL;DR: In this paper, a novel form of wavelength selectable diode laser source is proposed for wavelength division multiplexing (WDM) applications, which can operate at specific wavelengths across the complete gain spectrum of the laser diode material, but does not require any moving parts.
Abstract: A novel form of wavelength selectable diode laser source is proposed for wavelength division multiplexing (WDM) applications. The source may be used to operate at specific wavelengths across the complete gain spectrum of the laser diode material, but does not require any moving parts. Theoretical simulations indicate that the device can be expected to operate in a single longitudinal mode for channel separations on the order of 1 nm. The potential of using the device to generate parallel streams of WDM data is considered. >
TL;DR: In this article, simple methods to estimate amplification performances from only three basic erbium-doped fiber parameters are proposed and clarified that optical amplifiers greatly influence the development of future optical communication systems.
Abstract: Recent research on erbium-doped fiber amplifiers and their applications to trunk and distribution networks is described. Simple methods to estimate amplification performances from only three basic erbium-doped fiber parameters are proposed. It is clarified that optical amplifiers greatly influence the development of future optical communication systems. >
TL;DR: In this paper, the second-order distortion when an erbium-doped fiber amplifier (EDFA) is used to amplify the analog optical AM cable TV (CATV) multiple carrier signal from a directly modulated distributed feedback (DFB) semiconductor laser was investigated.
Abstract: The authors study the second-order distortion when an erbium-doped fiber amplifier (EDFA) is used to amplify the analog optical AM cable TV (CATV) multiple carrier signal from a directly modulated distributed feedback (DFB) semiconductor laser. Experimentally, it was seen that this second order distortion depends critically on the gain of the EDFA fiber amplifier. The authors attribute this distortion to the interaction between the frequency chirping of the DFB laser and the variable gain with wavelength of the amplifier. The authors describe an electronic predistorter that compensates the nonlinearity produced by the DFB-laser-EDFA combination. As a result, the high power advantage of the EDFA can be fully realized in spite of the potential for second-order distortion in the system. >
01 Feb 1991
TL;DR: In this paper, an erbium-doped optical fiber amplifier (EDFA) with a 0.98 micron laser diode with a strained-layer InGaAs quantum well laser structure has been developed as the pumping light source.
Abstract: Recent progress on an erbium-doped optical fiber amplifier (EDFA) pumped with a 0.98 micron laser diode is reported. An erbium-doped fiber with a very high gain coefficient of 11.0 dB/mW has been achieved using an extended VAD method. A high power 0.98 micron laser diode with a strained-layer InGaAs quantum well laser structure has been developed as the pumping light source. By employing these key components in the EDFA, a compact and highly efficient EDFA module has been fabricated successfully. The module size is only 36 cc. It attained a 33 dB net gain at 1.536 microns and it consumed only 175 mW of electricity.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the second-order intermodulation product, namely composite secondorder (CSO) distortion, is caused by coupling of the gain tilt of an erbium-doped fiber amplifier (EDFA) with laser chirp.
Abstract: It was found experimentally and theoretically that the second-order intermodulation product, namely composite second-order (CSO) distortion, is caused by coupling of the gain tilt of an erbium-doped fiber amplifier (EDFA) with laser chirp. When the signal light is not at the gain peak of the EDFA, gain tilt exists and EDFA cannot be used in an AM-FDM optical analog video transmission system because of CSO degradation. To counteract the gain tilt induced CSO, the authors demonstrated that codoping Al and setting the laser oscillation wavelength at the gain peak are useful. Er-Al-codoped fiber amplifiers have better linearity than Er-doped fiber amplifiers because the gain tilt of the former is smaller. >
AT&T1
TL;DR: In this paper, a fast tunable laser for packet switching applications based on wavelength division multiplexing (WDM) is presented, which can be switched randomly in less than 5 ns among these frequencies.
Abstract: A fast tunable laser for packet switching applications based on wavelength-division multiplexing (WDM) is presented. The laser is tunable to 16 discrete frequencies regularly spaced by 43 GHz over a tuning range of 645 GHz centred around a wavelength of 1.53 mu m. It can be switched randomly in less than 5 ns among these frequencies. Importantly, the same comb of frequencies is obtained from different lasers fabricated by the same lithographic process. This greatly simplifies the implementation of optical WDM systems.
TL;DR: In this article, a high density WDM multiplexer capable of combining 32 channels spaced 1 nm apart onto a monomode fiber is reported. But the multiplexers are not suitable for high frequency applications.
Abstract: A high density WDM multiplexer capable of combining 32 channels spaced 1 nm apart onto a monomode fibre is reported. The multiplexer incorporates a microlens array to give a channel bandwidth of 0.7 nm. The wavelength range of operation is 1.5285 mu m to 1.5595 mu m, within the erbium fibre amplification range. The mean insertion loss over the 32 channels is 6.7 dB and the polarisation sensitivity is less than 0.7 dB. >
01 Jan 1991
TL;DR: In this paper, the authors proposed a tunable wavelength-selective filters of Fabry-Perot interferometers with a liquid crystal intracavity, which provided high finesse (150-410), high transmittance (20-70%), narrow transmission peak (FWHM: 0.17-0.35 nm), and a large shift ( >SO nm) at a wavelength of 1.5 km.
Abstract: Optimum designs for tunable wavelength-selective filters of Fabry-Perot interferometers with a liquid crystal intracavity are de- scribed. The filters provide high finesse (150-410), high transmittance (20-70%), narrow transmission peak (FWHM: 0.17-0.35 nm), and a large shift ( >SO nm) at a wavelength of 1.5 km. These filters have a potential to select over 50 channels in WDM.
02 Dec 1991
TL;DR: The proposed approach introduces the concept of resolving reception conflicts by incorporating a delay line receiver design, which brings the optical star networks a step closer to all-optical realization.
Abstract: An original approach is proposed to controlling WDM (wavelength-division multiplexing) passive optical stars, termed queuing arrivals for delayed reception operation (QUADRO). In WDM stars the fundamental problem of receiver conflicts leads to severe performance degradation. In current solutions conflicts are prevented by scheduling transmissions or resolved by retransmissions. The proposed approach introduces the concept of resolving reception conflicts by incorporating a delay line receiver design. It thus brings the optical star networks a step closer to all-optical realization. In addition, it allows almost total utilization of the channels, as obtainable until now only by TDM. >
TL;DR: In this article, a multiple-wavelength 2*8 monolithic surface-emitting laser array with a potential aggregate array capacity of 80 Gb/s was reported, and the high-speed packaging for the array was made possible with a slip-chip bonding technique.
Abstract: A multiple-wavelength 2*8 monolithic surface-emitting laser array with a potential aggregate array capacity of 80 Gb/s is reported. The high-speed packaging for the array was made possible with a slip-chip bonding technique, and each laser was capable of 5 Gb/s operation. The chirp-broadened 20-dB spectral width was less than 0.3 mm and the spectra occupied 16 independent wavelengths. Both optical and thermal crosstalks were very small, and the electrical crosstalk ranged from >
Patent•
16 Jan 1991TL;DR: In this paper, an optical fiber point-to-multipoint (P2M) communications network with bus topology is described. But the authors do not consider the effect of the locations of the stations relative to the broadcasting terminal.
Abstract: An optical fiber point-to-multipoint communications network is disclosed of the type having a bus topology. The broadcasting terminal (101) of the network includes an information transmitting laser (102) and a local oscillator laser (103) the signals of which are launched onto opposite ends of an optical fiber bus (104) to counter-propagate thereon. At each of the M stations (105-1-105-M) connected to the bus, a wideband directional coupler (106-1-106-M) couples portions of each of the counter-propagating signals to a balanced coherent detector (107-1-107-M). The effective total power input to the balanced coherent detector at each of the stations is equal regardless of the location of the station relative to the broadcasting terminal. In another embodiment the stations are connected to ring-shaped optical subbuses which are coupled to the main bus. Several two-way point-to-multipoint embodiments are disclosed which employ wavelength division multiplexing techniques to enable communications from the stations back to the broadcasting terminal.
TL;DR: In this paper, the authors proposed an optical time-domain reflectometry (OTDR) scheme that uses new EDFAs containing optical circulators and return transmission lines, which support both OTDR and digital signal transmission.
Abstract: Fault location in optical amplifier transmission systems is described. Optical time-domain reflectometry (OTDR) cannot be used for an optical transmission line containing traditional Er-doped fiber amplifiers (EDFAs) because they contain optical isolators. The authors propose an OTDR scheme that uses new EDFAs containing optical circulators and return transmission lines. The new EDFAs support both OTDR and digital signal transmission. A 280.9 km transmission line containing three of the proposed EDFAs was constructed and tested. Experimental results demonstrated the feasibility of OTDR fault location and 1.8-Gb/s digital signal transmission. >
CNET1
TL;DR: In this paper, an optical wavelength convenor has been successfully operated up to 1.5Gbit/s using a two-electrode DFB laser, where an amplitude modulated (AM) input signal at 2.5171 μm was converted into a frequency modulated output signal at 0.5136 μm.
Abstract: An optical wavelength convenor has been successfully operated up to 1.5Gbit/s. This wavelength conversion used a two-electrode DFB laser where an amplitude modulated (AM) input signal at 1.5171 μm was converted into a frequency modulated (FM) output signal at 1.5136 μm.
TL;DR: In this article, a polarization independent narrow channel (PINC) wavelength division multiplexing (WDM) coupler for operation at 1.55 mu m has been designed based on the birefringent properties of fused single-mode couplers.
Abstract: A polarization-independent narrow-channel (PINC) wavelength division multiplexing (WDM) coupler for operation at 1.55 mu m has been designed based on the birefringent properties of fused single-mode couplers. These couplers are made from both conventional single-mode fiber (SMF) and dispersion shifted fiber (DSF). The couplers are designed so that the coupling-coefficient-length products for the two orthogonal polarizations are pi out of phase. As a result of the long coupling lengths required, these couplers have very small cross-sectional dimensions, typically on the order of 10 mu m. >
TL;DR: In this article, an electronically integrated, four-channel optical receiver is demonstrated which is designed for electronic channel selection of different wavelength channels in a wavelength-division-multiplexing-based optical network.
Abstract: A novel, electronically integrated, four-channel optical receiver is demonstrated which is designed for electronic channel selection of different wavelength channels in a wavelength-division-multiplexing-based optical network. The receiver consists of four InAlAs-InGaAs metal-semiconductor-metal (MSM) photodetectors that can be independently switched on or off electronically by a digital signal. An optical extinction ratio of 20 dB for the MSM detector was observed. The sensitivity of this optoelectronic integrated circuit receiver is -25.2 dBm at 1.2 Gb/s data rate. >
Patent•
12 Jun 1991TL;DR: In this paper, a method for fabricating a polarization independent narrow channel wavelength division multiplexing fiber optic coupler was proposed, comprising the steps of: holding two optical fibers in an abutting longitudinal relation along a predetermined length of the fibers, injecting light energy into one of them, fusing the optical fibers together along the predetermined length to form a fused length of a fiber optic coupling, elongating the fused length, and ceasing the fusing and elongating when the measured light energy output from the ends of the first and second fibers indicated that a predetermined number,
Abstract: The invention provides a method for fabricating a polarization independent narrow channel wavelength division multiplexing fiber optic coupler, comprising the steps of: holding two optical fibers in an abutting longitudinal relation along a predetermined length of the fibers; injecting light energy into one of the fibers; fusing the optical fibers together along the predetermined length to form a fused length of a fiber optic coupler; elongating the fused length of the fusing optical fibers; measuring the light energy output from the ends of the first and second fibers; ceasing the fusing and elongating when the measured light energy output from the ends of the first and second fibers indicates that a predetermined number, N S , of one-half power transfer cycles have occurred in the coupler, where the N S th one-half power transfer cycle occurs within a Kπ phase region of a polarization envelope associated with the coupler, where K is a positive integer.
TL;DR: In this article, the requirements and practicalities of amplifier cascades for multichannel coherent transmission are discussed, and a four-amplifier cascade which maintains an overall noise figure of less than 13 dB across a 20-nm optical bandwidth for total input powers up to -10 dBm is described.
Abstract: The requirements and practicalities of amplifier cascades for multichannel coherent transmission are discussed. A four-amplifier cascade which maintains an overall noise figure of less than 13 dB across a 20-nm optical bandwidth for total input powers up to -10 dBm is described. A potential capacity of 100 wavelength division multiplexing channels is demonstrated in a 300-km 622-Mb/s DPSK (differential phase shift keying) coherent transmission experiment. >
TL;DR: In this paper, an average power analysis technique similar to that used for semiconductor optical amplifiers was used to analyze both the discrete and the distributed fiber amplifier for multi-wavelength operation without the need for numerical integration.
Abstract: It is shown that an average power analysis technique similar to that used for semiconductor optical amplifiers can be used to analyze both the discrete and the distributed fiber amplifier for multiwavelength operation without the need for numerical integration. It is also shown to give results that are in excellent agreement with those from other studies. This approach gives performance insights that are not otherwise readily available. >
TL;DR: Cross-saturation characteristics are investigated in broadband 1.48-microm pumped and 980-nm pumped gainshaped erbium-doped fiber amplifiers and a degree of room-temperature spectral gain hole burning is observed for what is to the authors' knowledge the first time.
Abstract: Cross-saturation characteristics are investigated in broadband 1.48-µm pumped and 980-nm pumped gain-shaped erbium-doped fiber amplifiers. Gain shaping is shown to give a more uniform spectral gain compression on saturation. In addition, a degree of room-temperature spectral gain hole burning is observed for what is to our knowledge the first time.