Abstract: A four port optical add/drop multiplexer (OADM) includes an optical filter reflective at a first wavelength and transmissive at a second wavelength. An input path having both first and second wavelengths is routed toward a first side of the filter. An optical DROP path is routed from a second side of the filter, to carry the transmitted second wavelength from the filter; and an optical ADD path is routed toward the second side of the filter for carrying an ADD signal, at the second wavelength. An output path carries the first and second wavelengths from the first side of the filter, including the ADD signal at the second wavelength, providing full OADM functionality, using a single filter. The device may include collimating lenses in the signal paths, and in one embodiment the filter can be a thin film filter fabricated directly on one of these lenses, thus improving optical performance.

Abstract: A planar lightwave circuit generalized for handling any given band of multiple bands of a wavelength range, including a first grating element handling a first group of bands; and a second grating element handling a second group of bands. The first and second groups of bands overlap in the wavelength range, and may be spaced apart by a fixed wavelength value. By providing two periodic grating elements handling alternating bands, their free spectral range is allowed to expand, improving their roll-off characteristics. By providing separate inputs for each band, wavelength accuracy can be improved. Device flexibility can be further improved by using switch and interleaver fabrics at the inputs and outputs. The resultant device, generalized to handle any given band within a wavelength range, eliminates the need for separate component design and inventory tracking otherwise necessary.

Abstract: A groove assembly for holding at least one fiber optic. The assembly includes a base, a cover and a small carrier disposed between the base and the cover. The carrier has at least one groove. At least one fiber optic is disposed in this groove and terminates at an edge surface of the carrier. The base and cover have respective edge surfaces serving as attachment surfaces for attachment of the assembly to a planar lightwave circuit (PLC). The PLC has at least one waveguide terminating at an edge, to which the fiber requires alignment. The base and/or cover are preferably formed from a material enabling attachment to the PLC, e.g., transparent to energy used for curing an adhesive. The carrier is formed from material enabling a substantially more precise formation of the grooves, e.g., silicon.

Abstract: An optical component package, having an insulative buffer placed against the component, enclosing a first insulative cavity against a temperature-sensitive portion of the component. An outer package provides additional insulation for the component. The buffer may be formed of a soft insulative material, and pressed against the component by an inner surface of the outer package. For the PLC embodiments disclosed, the buffer is planar and includes a frame projecting from its perimeter toward the component to form the cavity. A heater may be positioned proximate the optical component to control its temperature, in which case a second buffer may be placed against the heater, enclosing a second insulative cavity against the heater, aligned with the temperature-sensitive portion of the component. The buffers and insulative cavities of the present invention provide important insulation for optical areas requiring precise temperature control for proper operation.

Abstract: A planar lightwave circuit includes at least one optical waveguide core, and at least one feature proximate the core having a stress-engineered property to balance stress and therefore minimize birefringence affecting the core. A protective passivation layer is formed over the core and the feature to be substantially non-interfering with the balanced stress provided by the feature. The stress balancing feature may be an overcladding layer formed over the core, doped to have a coefficient of thermal expansion approximately matched to that of an underlying substrate, to symmetrically distribute stress in an undercladding between the overcladding and the substrate, away from the core. The protective passivation layer is formed to have a coefficient of thermal expansion approximately matched to that of the overcladding. In one exemplary embodiment, the passivation layer is formed from silicon nitride. Related concepts of stress release grooves, and core overetching, are also disclosed.

Abstract: A redundant package for optical components includes an inner package enclosing the optical component, and an outer package enclosing the inner package. A heater may be disposed in the inner package proximate the optical component to control its temperature, and to maintain this temperature control, the outer package creates an isolated air pocket around the inner package which thermally insulates the inner package from the outside environment. The outer package is formed of a material having low thermal conductivity, to promote this insulating function. This package is especially useful if the optical component comprises a planar lightwave circuit (PLC), e.g., an arrayed waveguide grating (AWG), which requires tight temperature control and structural integrity to maintain the integrity of the optical paths.