Wavelength Division Multiplexing Devices Research Articles

Design considerations for Rowland circle gratings used in photonic integrated devices for WDM applications

Design issues of photonic integrated devices for WDM applications based on Rowland circle gratings have been studied. Effects of grating period, diffraction order, grating aperture (size), and Rowland circle size on device performance are discussed. The point spread function of a typical Rowland circle grating is evaluated numerically which yields an optical image (spot) size of several microns in diameter. Our study shows that there is a tradeoff between channel dispersion and feedback efficiency in choosing the grating period when a Rowland circle grating is used as the wavelength-selective element for a parallel-waveguide-type wavelength division multiplexing device. >

Calculation of channel separation in two-mode interference wavelength multiplexing devices

A theoretical study of two-mode interference wavelength division multiplexing (WDM) devices has been made. It is shown that the widely used approximate formula for the calculation of channel separation gives highly inaccurate results near the higher order mode cutoff. A more accurate formula is proposed for the calculation of channel separation. Using this formula, the effect of the depth of the channel waveguide on the channel separation is also studied. It has been found that the planar approximation of the channel waveguide underestimates the channel separation.

Uni- and bidirectional 4 lambda *560 Mb/s transmission systems using WDM devices based on wavelength-selective fused single-mode fiber couplers

Four-wavelength-channel wavelength-division multiplexing (WDM) lab transmission system experiments with buried heterostructure (BH) lasers at 1200-, 1240-, 1280-, and 1320-nm wavelengths, all-fiber WDM devices, and 20-km single-mode link fiber at a 560-Mb/s bit rate demonstrated that unidirectional and bidirectional WDM transmission systems could be operated successfully by using all-fiber 4 lambda multiplexing, 4 lambda demultiplexing, or 4 lambda multiplexing/demultiplexing devices with a low insertion loss per wavelength channel (2.1-4.7 dB), enough optical far-end crosstalk attenuation (18-37 dB), and high optical near-end crosstalk attenuation (43-49 dB). It is concluded that the four-wavelength-channel WDM lab transmission system at 560 Mb/s mainly used as a test bed is not representative of future unidirectional trunk WDM systems. Such systems favor distributed feedback (DFB) lasers in the 1500-1560-nm wavelength range where fiber attenuation is lower than in the 1200-1320 nm wavelength range and where 1500-nm DFB lasers with a smaller linewidth do not limit the repeater distance as much because of mode partition noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

RACE Project R1030, ACCESS-a system study of the broad-band subscriber loop

The ACCESS project, which is a project within the RACE (Research in Advanced Communication in Europe) program, is described. The scope of the project is to study the entire customer access connection, including the transmission, the multiplexing, and the passive optical network. The goal of the project is to perform an overall cost optimization, leading to one or more preferred implementations. Because the project is oriented toward the early phases of the integrated broadband network, the majority of the effort is spent on optimization and supplementation of present near-commercial technologies. The project involves 13 partners who share the work organized in three major areas, namely, the 622 Mb/s transmitter/receiver unit for bidirectional transmission on one single-mode (SM) fiber at 1330 and 1550 nm; the passive optical components, including mass splicing techniques, low-cost connectors, wavelength division multiplexing (WDM) devices, optical distribution frames, and optical cables; and system aspects of the frame structure and the interfaces to the customer premises network and to the exchange, with the associated functional units being the multiplexers and the broadband channel selector. >

Bragg gratings on InGaAsP/InP waveguides as polarization independent optical filters

The fabrication and operation of Bragg gratings for future wavelength-division multiplexing (WDM) devices in integrated optical circuits are discussed. Crosstalk attenuation of more than 20 dB with respect to the optical power and spectral bandwidths of up to 2.2 nm were achieved. Polarization-independent operation of the gratings, an important qualification for their operation in fiber optical transmission systems, was demonstrated with a filter bandwidth of 0.2 nm at -10 dB and channel spacings as small as 1 nm.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of bit error rate and power penalty for a birefringent wavelength division multiplexer

Abstract The power penalty and bit error rate degradation encountered when using wavelength division multiplexing devices is analyzed. Analysis is applied to the birefringent wavelength division multiplexer (BWDM) with a sinusoidal transfer function.1 The degradation in bit error rate is attributed to laser mode partition noise and crosstalk noise.

Wavelength multiplexing components - A review of single-mode devices and their applications

State-of-the-art and systems applications of single-mode wavelength-division multiplexing (WDM) devices are described. The performance characteristics required differ depending on whether the method of operation is one-way or two-way. Development trends and problems of the new technology are discussed.

Low-loss wavelength division multiplexing (WDM) devices for single-mode systems

We report here on single-mode microoptic wavelength division multiplexing (WDM) devices with two channels located at 1275 and 1345 nm, respectively. Data are presented for four multiplexers and four demultiplexers. The average insertion loss for the multiplexers was 0.5 ± 0.2 and 1.0 ± 0.3 dB for the short and long wavelength channels, respectively. For the demultiplexers, the average losses were 0.8 ± 0.2 dB and 1.0 ± 0.1 dB, respectively. The full channel widths of the demultiplexers for 0.5 dB of additional loss were about 22 nm. All measurements included the presence of prototype precision single-mode connectors. The multiplexers were based on interference filters and GRIN lenses with identical single-mode fibers used for inputs and output. The demultiplexers employed diffraction gratings and GRIN lenses with 50- μm core graded-index output fibers. In addition three of the demultiplexers included a third output channel centered at 1521 nm. The 28- dB dynamic range of the monochromator-based test appartus was insufficient to evaluate the crosstalk performance. Measurements on two demultiplexers, using a 1295-nm laser, yielded values of -33 and -38 dB, respectively for the crosstalk in the 1345-nm channel.