Presents a new category of optical CDMA systems which work based on spectral encoding. In such systems, that the authors refer to as frequency-encoded CDMA (FE-CDMA) systems, the coding is done in the frequency domain while in the usual CDMA systems the code multiplies the modulation signal in the time domain. They present a new type of FE-CDMA system, based on encoding noncoherent broadband sources. They discuss the advantages of the system compared to other optical CDMA systems and present its performance. They show that very efficient, low-cost, CDMA systems can be obtained with an aggregate throughput of many gigabits per second. Also, for this system, the spreading gain of CDMA is independent of the modulation bandwidth. Hence, the system can accommodate variable bit rates, naturally. >

Optical code-division-multiplexed systems based on spectral encoding of noncoherent sources

An approach to the realization of a broadband, flexible, multiwavelength transport network employing an optical network layer. The design methodology for a network demonstrator is presented, and the transmission, switching, line, and management/supervisory subsystems and components are described. >

A transport network layer based on optical network elements

A optical code-division multiple access (CDMA) system based on amplitude spectral encoding of low-cost broadband sources such as light-emitting diodes is presented. The proposed system uses a standard nondispersive lens-grating apparatus and simple direct-detection receivers. It is shown that by assigning to N subscribers the N cycles shifts of a single unipolar m-sequence of period N, complete orthogonality between the users can be achieved, provided that the spectrum is properly equalized. It is also shown that without any equalization, and for N=511, up to 200 users can transmit asynchronously with an average error probability equal to 10/sup -9/, depending on the received power level. An aggregate network throughput of 100 Gb/s can therefore be obtained. >

An optical CDMA system based on spectral encoding of LED

A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.

Multi-wavelength light amplifier

A gain-flattened Er/sup 3+/-doped silica-based fiber amplifier (EDFA) has been constructed for a 1.58-/spl mu/m band WDM signal. This EDFA exhibits uniform amplification characteristics with a gain excursion of 0.9 dB for a four-channel WDM signal in the 1.57-1.60 /spl mu/m wavelength region. The average signal gain and the noise figure for the WDM signal are 29.5 dB and less than 6.3 dB, respectively. The use of this EDFA in parallel with a 1.55-/spl mu/m band EDFA will expand the WDM transmission wavelength region.

Gain-flattened Er/sup 3+/-doped fiber amplifier for a WDM signal in the 1.57-1.60-μm wavelength region

An acoustooptic tunable filter is used to compensate for the gain spectrum variations in multiwavelength lightwave systems containing cascaded fiber amplifiers. Demonstrations of such systems using a circulating loop containing a fiber amplifier and an acoustooptic tunable filter have shown that differential gain compensations of up to 14 dB can be achieved for two arbitrary injected wavelengths. >

Gain equalization multiwavelength lightwave systems using acoustooptic tunable filters

An acoustooptic tunable filter is used to compensate for the gain spectrum variations in multiwavelength lightwave systems containing cascaded fiber amplifiers. Demonstrations of such systems using a circulating loop containing a fiber amplifier and an acoustooptic tunable filter have shown that differential gain compensations of up to 14 dB can be achieved for two arbitrary injected wavelengths.<<ETX>>

Gain Equalization in Multiwavelength Lightwave Systems Using Acous toop tic Tunable Filters

An acousto-optic tunable filter is employed to flatten the gain spectrum of an erbium-doped fibre amplifier. A relatively flat gain spectrum of 15 nm in bandwidth with variations of less than 1 dB is obtained by simultaneously applying eight closely-spaced RF signals to the acousto-optic tunable filter.

S. F. Su

Papers

Gain equalization multiwavelength lightwave systems using acoustooptic tunable filters

Gain Equalization in Multiwavelength Lightwave Systems Using Acous toop tic Tunable Filters

Flattening of erbium-doped fibre amplifier gain spectrum using an acousto-optic tunable filter

Use of acoustooptic tunable filters as equalizers in WDM lightwave systems