Advances in telecom and datacom optical components

We review and contrast key technologies developed to address the optical components market for communication applications. We first review the component requirements from a network perspective. We then look at different material systems, compare their properties, and describe the functions achieved to date in each of them. The material systems reviewed include silica fiber, silica on silicon, silicon on insulator, silicon oxynitride, sol-gels, polymers, thin-film dielectrics, lithium niobate, indium phosphide, gallium arsenide, magneto-optic materials, and birefringent crystals. We then describe the most commonly used classes of optical device technology and present their pros and cons as well as the functions achieved to date in each of them. The technologies reviewed include passive, actuation, and active technologies. The passive technologies described include fused fibers, dispersion-compensating fiber, beam steering, Bragg gratings, diffraction gratings, holographic elements, thin-film filters, photo...

Optical communication components

In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.

Optical transmission apparatus, optical transmission system, and optical terminal station

Through the efforts of many research groups and consortia over the last several years, the acousto-optic tunable filter has evolved into a device capable of high-performance wavelength-selective optical switching and wavelength routing in dense WDM systems. The distinguishing feature of the AO switch is its ability to sustain many independent coexisting passbands, thus allowing in a simple integrated-optic device, the parallel processing capability of much more complex designs. The AOTF has also found a role in active gain equalization of optically amplified networks. In this paper, we review the design of both hybrid and fully integrated AO switches. The theory of operation is reviewed and recent advances in passband engineering are described which have made low-crosstalk, wavelength misalignment-tolerant switches to be possible. Advanced issues such as mechanisms of interchannel crosstalk and its reduction are also discussed. Both device and system issues are covered.

Evolution of the acousto-optic wavelength routing switch

An acousto-optic filter has a non-birefringent single mode optical fiber with a longitudinal axis, a core and a cladding in a surrounding relationship to the core. The optical fiber has multiple cladding modes and a single core mode that is guided along the core. An acoustic wave propagation member has a proximal end and a distal end coupled to the optical fiber. The acoustic wave propagation member propagates an acoustic wave from the proximal to the distal end and launches a flexural wave in the optical fiber. At least one acoustic wave generator is coupled to the proximal end of the acoustic wave propagation member.

Acousto-optic filter

Multiple wavelength filtering/switching can be obtained using integrated acousto-optical wavelength filters and switches in LiNbO/sub 3/ by driving them with several RF signal simultaneously. As a consequence, interchannel interference occurs due to the interaction of several acoustic waves within the same mode converter resulting in an intensity modulation of the transmitted optical waves. System performance can be degraded as this interchannel interference leads to a power penalty equivalent to an additional cross talk. We present the coupled-mode analysis of the interchannel interference in the multiwavelength operation of acousto-optical filters and switches. Theoretical models are developed and confirmed by experimental results. Furthermore, the impact on WDM system performance is studied by measuring bit error rate characteristics and comparing the results with the theory. >

F. Tian

Papers

Interchannel interference in multiwavelength operation of integrated acousto-optical filters and switches