Abstract: A new architecture is proposed for an optical node in a wavelength division multiplexed network. The optical node may be an optical add/drop node. Conventional add/drop nodes utilize one of two architectures—broadcast and blocking. The broadcast architecture is an architecture in which a copy of an optical signal is dropped to a drop path of a node while another copy continues on a through path. Thus, channels that occupy a specific portion of wavelengths (or spectrum) prior to the node are not available for use subsequent to the add/drop connectivity. In a blocking architecture, at least the through path (and often the drop path) is spectrally filtered. This permits wavelength reuse for add/drops in subsequent portions of the network. This disclosure proposes an optical node architecture that enables starting out with a low cost approach, such as broadcast, but includes connections to permit ‘in-service’ upgrade to more capable architecture. Increasing spectral reuse is enabled through the architecture.

Abstract: An optical communication device, and related method, are provided for reducing ripple in WDM systems. In particular, the optical communication device includes a dynamic gain equalization (DGE) circuit is coupled to an optical communication path carrying the WDM optical signals. The DGE circuit adjusts the powers associated with each channel on a channel-by-channel basis so that the WDM optical signal has a desired power spectrum. The DGE is controlled in response to sense signals generated by an optical performance monitoring (OPM) circuit located downstream from the DGE or substantially co-located with the DGE. The OPM monitors the WDM spectrum for optical signal power variations and outputs the sense signal when the variations fall outside a given tolerance. Typically, one DGE is associated with a group of concatenated amplifiers so that multiple DGEs are provided in a system having many groups of such amplifiers.

Abstract: A new fiber optic based beamforming architecture for a time steered phased rray antenna based on chirped fiber gratings. All of the gratings are identical in length and period chirp so that they all have the same dispersion, thus at a given optical wavelength they have the same time delay. In a preferred embodiment an optical signal is modulated with an RF signal. The RF modulated optical is split and a portion propagates through a length of fiber to a photodetector feeding an antenna array. The second portion of the optical signal is routed through a circulator, which feeds the optical signal to a chirped fiber grating. The grating reflects and delays the optical signal back to the circulator which routes the reflected optical signal to a second coupler. The amount of delay incurred is determined by the grating dispersion and the wavelength of the optical source.

Abstract: An improvement to a precise optical tracking system is described. The system is comprised of a three-sided transparent pyramid with a sharp vertex. The pyramid is used to split the incident beam into three parts, which are transmitted to respective photodetectors. The signals from the photodetectors are used for tracking. This invention makes several important improvements to an optical tracking system. The amount of energy incident on each photodetector is increased by 33% over a known four-detector system. The sensor inherently possesses a point vertex formed by three inclined surfaces, regardless of manufacturing tolerances. This directly contributes to increased sensor accuracy in comparison to known four-sided splitters. By reducing the number of sensors to three, the system's mechanical and electronic size and complexity is reduced.

Abstract: A precision optical tracking, stabilization, focusing, and information receiving system is described. This invention is designed to improve optical systems in two important areas. The first application is in systems that require both reception of information and target tracking using a single beam. A transparent pyramid with a truncated vertex (frustum of a pyramid) is used to split a beam into 5 parts. The central axial part is used as an information carrier, and the other four are used for tracking. The second application is for precise focusing. The light beam is focused onto the vertex of a frustum of a pyramid and the intensity of the central fraction of the beam, as compared with the side fractions, decreases as the focal point is moved away from the surface of the pyramid in either direction.