The very broad bandwidth of low-loss optical transmission in a single-mode fiber and the recent improvements in single-frequency tunable lasers have stimulated significant advances in dense wavelength division multiplexed optical networks This technology, including wavelength-sensitive optical switching and routing elements and passive optical elements, has made it possible to consider the use of wavelength as another dimension, in addition to time and space, in network and switch design The independence of optical signals at different wavelengths makes this a natural choice for multiple-access networks, for applications which benefit from shared transmission media, and for networks in which very large throughputs are required Recent progress in multiwavelength networks are reviewed, some of the limitations which affect the performance of such networks are discussed, and examples of several network and switch proposals based on these ideas are presented Discussed also are critical technologies that are essential to progress in this field >

Dense wavelength division multiplexing networks: principles and applications

https://engineering.purdue.edu/~fsoptics/articles/Ultrafast_optical_pulse_shaping_tutorial-Weiner.pdf

Ultrafast optical pulse shaping: A tutorial review

Femtosecond optical pulse shaping and processing

An architectural approach for very-high-capacity wide-area optical networks is presented, and a proposed program of research to address key system and device issues is described. The network is based on dense multiwavelength technology and is scalable in terms of the number of networked users, the geographical range of coverage, and the aggregate network capacity. Of paramount importance to the achievement of scalability are the notions of wavelength reuse and wavelength translation. A distributed optical interconnect that is wavelength-selective and electronically controllable, permitting the same limited set of wavelengths to be reused among other access stations, is employed. By exercising the wavelength-selective switches, the wavelength-routed connectivity between stations can be reconfigured as needed. A multihop overlay network involving wavelength translation and self-routing fast packet switches permits full connectivity, if desired among the access stations at the individual virtual circuit level. Using just eight wavelengths, such a network could in principle interconnect a population of 100 million users over a nationwide geography with an expected delay equal to that of 12 hops. >

A scalable multiwavelength multihop optical network: a proposal for research on all-optical networks

The different approaches being considered to build high-capacity lightwave networks are described. Two kinds of lightwave network architectures are examined: broadcast-and-select networks and wavelength-routing networks. A comparison of the two shows that broadcast-and-select networks may be more suitable for local area networks (LANs) and metropolitan area networks (MANs), while wavelength-routing networks are suitable for wide area networks (WANs). The overall network may then be a combination of broadcast subnets interconnected by a point-to-point wavelength-routing network. >

Multiwavelength lightwave networks for computer communication

Recent advances in fully integrated acoustically tuned optical filters (ATOFs) for use in wavelength-division multiplexing (WDM) are reviewed. Experiments in parallel processing of wavelength channels are described. The ATOF uses the photoelastic effect induced by a surface acoustic wave (SAW) to flip the polarization state of a narrow phase-matched band of wavelengths. A unique feature of the ATOF is that many wavelengths can be simultaneously and independently processed, because the associated SAW beams can be superimposed with negligible interaction at the drive levels required for complete polarization conversion. This parallel processing capability has been used to select as many as five out of eight laser channels in an experiment in which each channel was tagged by a separate microwave subcarrier. Polarization-independent devices are also discussed. A polarization-diversity ATOF that decomposes an input beam into TE (horizontal) and TM (vertical) components, interchanges TE and TM roles for the resonant wavelength, and reroutes the filtered beam into a spatially distinct port is described. >

Integrated-optic acoustically-tunable filters for WDM networks

We demonstrate a narrowband (≈1 nm) LiNbO3 acoustically tunable optical filter with a tuning range adequate to span the 1.3–1.55 μm wavelength range, exploiting the considerable advantages of an unconventional x-cut design.

Integrated-optic acoustically tunable infra-red optical filter

Demonstrates an integrated bulk-wave acousto-optic tunable filter (1.0 nm FWHM) in a multiwavelength crosstalk measurement experiment. With 16 channels present, individual channel crosstalk was lower than -15 dB for both single-wavelength and dual-wavelength filtering. The RF drive power for 70% efficiency was 180 mW/wavelength. >

Multiple channel operation of integrated acousto-optic tunable filter

A polarization‐independent acoustically tunable optical filter is described, with 1.3 nm bandwidth and 145 nm tuning range demonstrated about a center wavelength of 1525 nm. Filtered and unfiltered beams exit from different ports of this 2×2 integrated‐optic structure fabricated on a LiNbO3 substrate. The filter conversion efficiency was 97% for unpolarized light, limited by imperfect splitting of the directional‐coupler polarizing beamsplitters. Using an unpolarized, 105‐nm‐wide light‐emitting diode as the optical source, 16 dB isolation of the filtered port was achieved, both with respect to the nearest nulls and the remote background spectrum.

Polarization‐independent acoustically tunable optical filter

Demonstrates a two-stage integrated-optic acoustically tunable infra-red optical filter with subnanometre bandwidth and -19 dB sidelobe suppression. This configuration also eliminates the optical frequency shift of one-stage devices.

J.E. Baran

Papers

Integrated-optic acoustically-tunable filters for WDM networks

Integrated-optic acoustically tunable infra-red optical filter

Multiple channel operation of integrated acousto-optic tunable filter

Polarization‐independent acoustically tunable optical filter

Two-stage integrated-optic acoustically tunable optical filter with enhanced sidelobe suppression