A GTIFR interferometer, for use in an interleaver or in a deinterleaver, wherein the GTIFR interferometer includes a Gires-Toutnois interferometer with a 45 degree Faraday rotator between the mirrors of the Gires-Tournois interferometer and further includes a 22.5 degree Faraday rotator in the light path to the Gires-Tournois interferometer and an interleaver or deinterleaver that contains one GTIFR. A dispersion compensated GTIFR interleaver includes a second Gires-Tournois interferometer for providing chromatic dispersion compensation.

A GTIFR interferometer, for use in an interleaver or in a deinterleaver, wherein the GTIFR interferometer includes a Gires-Toutnois interferometer with a 45 degree Faraday rotator between the mirrors of the Gires-Tournois interferometer and further includes a 22.5 degree Faraday rotator in the light path to the Gires-Tournois interferometer and an interleaver or deinterleaver that contains one GTIFR. A dispersion compensated GTIFR interleaver includes a second Gires-Tournois interferometer for providing chromatic dispersion compensation.

The present invention provides an improvement in the separation mechanism to be used in a dense wavelength division multiplexer. The separation mechanism in accordance with the present invention includes an asymmetric pass band interferometer. The interferometer includes a first glass plate optically coupled to a second glass plate, forming a space therebetween; a first reflective coating with a first reflectivity residing inside the space and on the first glass plate; a second reflective coating with a second reflectivity residing inside the space and on the second glass plate; a first waveplate with a first optical retardance residing inside the space; and a second waveplate with a second optical retardance, optically coupled to the first glass plate and residing outside the space, where a combination of values for the first reflectivity, the first optical retardance, and the second optical retardance effect a separation of channels in at least one optical signal into at least two sets, and where the at least two sets have asymmetrically interleaved pass bands. The asymmetric pass band interferometer in accordance with the present invention is capable of separating channels from signals with different data transfer rates. With the present invention, a maximum use of available bandwidth on an optical fiber may be accomplished. An added functionality of the asymmetric pass band interferometer of the present invention is the ability to facilitate an asymmetric or uneven add/drop function while also separating the channels.

An airgap type etalon has a higher degree of design freedom of a wavelength-temperature characteristic so that such a wavelength-temperature characteristic can be freely adjusted. The airgap type etalon includes a fixing block having one flat surface, and a transparent parallel flat plate having parallel flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively. The flat surface at the antireflection coating side is joined to the flat surface of the fixing block. A parallel flat spacer has a thickness greater than that of the transparent parallel flat plate and an expansion coefficient different from that of the transparent parallel flat plate. One of the flat surfaces of the parallel flat spacer is joined to the flat surface of the fixing block. A transparent flat plate has opposite flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively. The flat surface at the reflection augmenting coating side is joined to the other of the flat surfaces of the parallel flat spacer, wherein a Fabry-Perot interferometer is formed based on an airgap positioned between the flat surface of the transparent parallel flat plate and the flat surface of the transparent flat plate, which flat surfaces face each other.

Phase and free spectra range adjustable reflectors, referred to herein as nano tuner (NanoT) reflectors, provide building blocks for the manufacturing of passive and active devices used for dense wavelength division multiplexing applications. Specifically, NanoT can be used to fabricate interleavers, multichannel filters and dispersion compensators, optical spectrum synthesizers and other valuable devices. Various embodiments are disclosed. Each provides at least one hermetically sealed optical cavity connected to a tuning device through a channel. The tuning device permits modification to the density of an optical medium contained in the cavity. In the preferred embodiments disclosed, the optical medium comprises one or more selected gases which determine the index of refraction in the cavity. The cavity is formed between two optical windows having facing surfaces coated by partially or wholly reflective coatings. The facing surfaces are separated by a selected distance by a precise spacer. In some embodiments, two cavities are employed and each may contain a wave plate or phase plate.