An optical filter device may include an optical fiber having a core and a cladding surrounding the core, the optical fiber having a tapered portion. The optical filter device may include an index selectable material surrounding the tapered portion and having an index of refraction being selectable based upon a physical characteristic. The optical filter device may include a device configured to change the index selectable material to select the index of refraction to selectively filter out a mode within the optical fiber.

A supercontinuum optical pulse source provides a combined supercontinuum. The supercontinuum optical pulse source comprises one or more seed pulse sources (13), and first and second optical amplifiers (7) arranged along first and second respective optical paths. The first and second optical amplifiers are configured to amplify one or more optical signals generated by said one or more seed pulse sources. The supercontinuum optical pulse source further comprises a first microstructured light-guiding member (9) arranged along the first optical path and configured to generate supercontinuum light responsive to an optical signal propagating along said first optical path, and a second microstructured light-guiding member (9) arranged along the second optical path and configured to generate supercontinuum light responsive to an optical signal propagating along said second optical path. The supercontinuum optical pulse source further comprises a supercontinuum-combining member (5) to combine supercontinuum generated in at least the first and second microstructured light-guiding members to form a combined supercontinuum. The supercontinuum-combining member comprises an output fibre, wherein the output fibre comprises a silica-based multimode optical fibre supporting a plurality of spatial modes at one or more wavelengths of the combined supercontinuum.

An electro-optical single-sideband modulator (1) comprising:

• an electro-optical substrate (2) ;

• a bimodal optical waveguide structure (3) formed in the substrate (2) to support different optical modes having associated optical frequencies (ω_S, ω_A) and optical propagation constants (β_S, β_A) and comprising an optical input (IN) to receive an input optical carrier signal having an optical frequency (ω_S), and a pair of optical outputs (OUT1, OUT2) to output corresponding SSB modulated optical signals, each having an optical frequency spectrum with a single side lobe; and

• an electrode structure (4) formed on the substrate (2) to receive an input electrical modulating signal having an associated electrical frequency (Ω) and electrical propagation constant (β_Ω), and to responsively apply an electrical field to the bimodal optical waveguide structure;

wherein the bimodal optical waveguide structure (3) and the electrode structure (4) are so formed that the optical propagation constants (β_S, β_A) of the optical modes and the electrical propagation constant (β_Ω) of the electrical modulating signal meet a Phase Matching condition, according to which the optical propagation constant (β_A) of a first one of the optical modes is equal to the sum of the optical propagation constant (β_S) of a second one of the optical modes and the electrical propagation constant (β_Ω) of the electrical modulating signal, so resulting in the energy of the first optical mode being transferred at least partially to the second optical mode, and, as a consequence, in the optical frequency (ω_A) of the second optical mode being equal to the optical frequency (ω_S) of the first optical mode up-shifted of the electrical frequency (Ω) of the electrical modulating signal.

A planar core and a cladding disposed on opposite sides of thereof. In the best mode, the rotator includes a very low Numerical Aperture (NA) planar waveguide. The cladding is birefringent and the refractive index and birefringence thereof are optimized to provide equal mode propagation velocities for both TE and TM modes for at least one transverse mode. The refractive index and birefringence of the cladding are optimized to provide equal mode propagation velocities for both TE and TM modes for a wide range of transverse modes.

A planar core and a cladding disposed on opposite sides of thereof. In the best mode, the rotator includes a very low Numerical Aperture (NA) planar waveguide. The cladding is birefringent and the refractive index and birefringence thereof are optimized to provide equal mode propagation velocities for both TE and TM modes for at least one transverse mode. The refractive index and birefringence of the cladding are optimized to provide equal mode propagation velocities for both TE and TM modes for a wide range of transverse modes.

System and methods for all-optical signal regeneration based on free space optics are described. In one exemplary embodiment, a method for regenerating an optical signal comprises counter-propagating an input signal and a regenerating signal within an all-optical signal regenerator based on free space optics, where the all-optical signal regenerator based on free space optics comprises a Sagnac loop interferometer, and extracting a regenerated output signal from the Sagnac loop interferometer. In another exemplary embodiment, an all-optical signal regenerator based on free space optics comprises a Sagnac loop interferometer, an optical signal input path coupled to a semiconductor optical amplifier of the Sagnac loop interferometer, a regenerating optical signal path coupled to the semiconductor optical amplifier of the Sagnac loop interferometer, and a regenerated optical output path coupled to the Sagnac loop interferometer.

The present invention provides a set-reset flip-flop operating in an all-optical manner. In this invention, a set pulse is inputted from the setting port. In doing so, only oscillation in setting mode is generated at the multi-mode interference portion in waveguide. As a result, a non-inverting output Q is obtained from the non-inverting output port. This state is then continued even if the set pulse input goes off. Next, a reset pulse is inputted to the resetting port. In doing so, at the multi-mode interference portion, oscillation of light in the set mode is halted, and oscillation in the reset mode occurs. As a result, it is possible to obtain an inverting output Q-bar from the inverting output port. This state is then continued even if the reset pulse goes off.