US 2009/0263142 A1 · TUNABLE OPTICAL FILTER

Abstract

A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter.

Claims24

Dependent claims

A tunable optical filter for selecting any single optical frequency channel from a plurality of equidistantly spaced optical frequency channels of an optical signal, each said optical frequency channel having a central frequency, the filter comprising:

a plurality of sequentially coupled tunable Mach-Zehnder (MZ) interferometers each having a plurality of equidistantly spaced conterminous frequency passbands and frequency stopbands,
wherein the MZ interferometers are tunable so as to have one passband of each MZ interferometer centered on the central frequency of the single frequency channel being selected, and to have at least one of the stopbands of the MZ interferometers centered on the central frequency of each remaining optical frequency channel of the optical signal, so as to suppress each said remaining optical frequency channel of the optical signal.

A method of selecting a single optical frequency channel from a plurality of optical frequency channels of an optical signal, each said optical frequency channel having a central frequency, the method comprising:

(a) providing a chain of sequentially connected tunable Mach-Zehnder (MZ) interferometers each having a plurality of equidistantly spaced conterminous frequency passbands and frequency stopbands, said chain having an input end and an output end;
(b) coupling the optical signal to the input end of the chain;
and
(c) centering one passband of each tunable MZ interferometer on the central frequency of the single optical frequency channel of the optical signal, so as to have at least one of the stopbands of the tunable MZ interferometers centered on the central frequency of each remaining optical frequency channel of the optical signal, so as to suppress each said remaining optical frequency channel of the optical signal.

1 more element

Dependencies are inferred from the claim text.

Tunable optical filter

Life of this patent

Tunable optical filter

Life of this patent

Abstract

Claims24