Abstract: An exemplary embodiment of the invention is an optical filter including a mirror including a plurality of first dielectric layers having a first index of refraction and a plurality of second dielectric layers having a second index of refraction. A plurality of the first dielectric layers have an integer quarter wave optical thickness and at least one of the first dielectric layers has a non-integer quarter wave optical thickness. A plurality of the second dielectric layers have an integer quarter wave optical thickness and at least one of the second dielectric layers has a non-integer quarter wave optical thickness. In an exemplary embodiment, the non-integer quarter wave optical thickness first layer and the non-integer quarter wave optical thickness second layer are determined so as to enhance transmission at a predetermined wavelength.

Abstract: A dual-band optical filter is disclosed which has two transmission bands. The first band is relatively narrow (about 1 nm) and encompasses a wavelength of about 1550 nm, while the second band is relatively broad (greater than 50 nm) to transmit wavelengths in a range of 1300-1400 nm. Accordingly, the filter can be used in wavelength division multiplexed communication systems to simultaneously select a payload channel having a wavelength of approximately 1550 nm, and a 1310 nm service channel.

Abstract: An optical interference filter having high transmissivity at first and second passbands. The interference filter includes a first stack having a plurality of dielectric layers, a second stack having a plurality of dielectric layers, and a spacer interposed between the first and second stacks. Each of the dielectric layers included in the first and second stacks have optical thicknesses which vary quadratically. The dielectric layers have alternating high and low refractive indices.

Abstract: A WDM ring configuration having a central office node is provided in which each channel has substantially the same loss and no single channel has a disproportionately high loss. Thus, the diameter of the WDM ring in accordance with the present invention can be increased and/or the number of filters provided along the ring can be increased to accommodate additional channels.

Abstract: An optical filter having broad resonant frequency passbands for filtering an optical input including a plurality of multiplexed optical wavelengths into a first set of transmitted wavelengths and a second set of reflected wavelenghts. The filter has first and second inner mirrors separated substantially by an inner spacer, a first outer mirror separated from the first inner mirror substantially by a first outer spacer, and a second outer mirror separated from the second inner mirror substantially by a second outer spacer. The inner mirrors have reflectivity which is greater than the reflectivity of the outer mirrors, and are formed from layers of alternating high and low refractive index materials. The optical thicknesses of the spacers are substantially identical, and are sized to align the resonant frequency passbands of the filter with the first set of transmitted wavelengths.