Abstract: Overlapping multiple fiber Bragg gratings for reflecting light in a plurality of wavelength each with a selected narrow linewidth are described. Each fiber Bragg grating has a selected period so as to reflect light in a wavelength with a selected narrow linewidth. The overlapping multiple fiber Bragg gratings can be used in various applications, including a multiwavelength laser source. One embodiment of a multiwavelength laser source includes a laser diode having first and second facets from which output light is emitted and an optical fiber section having an end located near the second facet to receive output light from the laser diode. The optical fiber section includes overlapping multiple fiber Bragg gratings for reflecting output light in the wavelengths with selected narrow linewidths back into the laser diode through its second facet. The output light emitted from the first facet has very narrow linewidths about the selected linewidths.

Abstract: An add/drop device is described that allows channels from a multi-channel optical path to be dropped to a device and a new or modified channel to be added to the multi-channel optical path. The device thereby has access to a channel from the multi-channel optical path without having access to all of the channels. In one embodiment, the add/drop device of the invention includes one or more intermediate ports and a switch. The intermediate ports communicate the channels not dropped by the add/drop device and the switch selectively optically couples the dropped channel either to the device or to be added back into the multi-channel path. The switch also selectively optically couples the new or modified channel to be added to the multi-channel path. The one or more intermediate ports allow multiple add/drop devices to be optically coupled together to provide a configurable add/drop mechanism.

Abstract: An apparatus that features an optical fiber with a core surrounded by a cladding, wherein at least one of the core and the cladding has a reduced thickness along an interval of the fiber to enlarge a modal field diameter of the guided mode in the fiber. A control layer is disposed on an external surface of the cladding along the interval. The control layer exhibits a strong change in its index of refraction as a function of temperature. The apparatus further includes a heating/cooling element and a controller to change the temperature of the control layer to more than two different levels, responsive to more than two different, corresponding attenuation settings for an optical signal to be guided by the fiber. In another embodiment of the invention, a coreless optical fiber is fused to the cladding of the optical fiber at the interval to achieve a flat wavelength response behavior.

Abstract: An interleaver and a deinterleaver for filtering optical signals are described. The interleaver separates subsets of channels. The deinterleavers mix subsets of channels. Interleavers and deinterleavers can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: The invention provides an optical attenuator having a pair of substantially parallel mirrors that attenuate an optical signal based, at least in part, on the rotation angle of the mirrors. When the pair or mirrors is in a predetermined position, an input optical signal is directed from an input port to an output port with a minimum insertion loss. As the pair of mirrors is rotated, the optical signal is shifted parallelly, which provides increased insertion loss and an attenuated signal at the output port. The pair of mirrors can be rotated, for example, with a stepper motor, or other device.