Abstract: A tunable filter structure comprising of a rotating disk made of metal parts in which N diffractive elements like bulk gratings are adjusted and mounted individually to disperse the incoming light and form a Littman-Metcalf configuration for selecting different wavelength of light, a servo motor to rotate the disk, a reflective element like mirror and a multi-branch configuration comprising of M branches that are synchronized in time and are combined by an optical coupler or an optical switch. In the second embodiment, the diffractive elements are replaced by the reflective elements to form a Littrow configuration. The tunable filter can be used in combination of a gain medium like semiconductor optical amplifier (SOA) or an Erbium-doped fiber amplifier (EDFA), in a ring or linear configuration to make a sweeping light source with low cost and high sweeping frequency.

Abstract: A new type of optical pressure sensor with adjustable sensitivity is proposed based on the fiber Bragg grating (FBG). In this technique, the pressure changes the length of a metal bellows which is placed behind a spring. The fiber grating is fixed over the bellows between a fixed position and the connection point of bellows and spring. The wavelength change of FBG is caused by the change in the bellows length; however, the spring controls the total length expansion of the bellows. It will bring two benefits: first it is easy to change the pressure sensing range by changing the spring rate; and secondly the spring improves the linearity of the wavelength sift due to the pressure. The FBG is installed outside of the bellows and is not in contact with the material in which the pressure should be measured (gas or liquid) in contrast with other pressure sensors where the FBG is inside the bellows.

Abstract: A new type of tunable fiber Bragg grating (FBG) is proposed based on the compression of FBG from both sides. In this technique, the FBG is compressed from both sides simultaneously which provides the more uniform force distribution along the grating compared to the compression from one side. As a result, the grating period changes uniformly due to compression and the same spectral shape can be achieved over a wide spectrum. The double-sided compression technique represents a significant improvement over the prior wavelength tunable fiber grating techniques, especially for the long gratings.

Abstract: A technique for processing optical input signals to produce optical output signals using only a single hologram for a plurality of circularly shifted code words used to encode the input signals. A spatial light modulator coupled to the each of the optical input signals encodes a corresponding one of the input optical signals, and the optical signals are linear combined for further processing. A matched filter composed of the single hologram receives the linear combination, and a two-dimensional microlens arrangement coupled to the matched filter emits each of the optical output signals from a corresponding microlens in the arrangement. Switching is engendered by controlling each spatial light modulator to thereby direct each input signal to the desired one of the microlens in the arrangement.

Abstract: A technique for processing optical input signals to produce optical output signals using only a single hologram for a plurality of circularly shifted code words used to encode the input signals. A spatial light modulator coupled to the each of the optical input signals encodes a corresponding one of the input optical signals, and the optical signals are linear combined for further processing. A matched filter composed of the single hologram receives the linear combination, and a two-dimensional microlens arrangement coupled to the matched filter emits each of the optical output signals from a corresponding microlens in the arrangement. Switching is engendered by controlling each spatial light modulator to thereby direct each input signal to the desired one of the microlens in the arrangement.