A method for converting electromagnetic (EM) energy between guided modes of a photonic crystal waveguide (800) having a waveguide axis (810), the method including: (i) providing the photonic crystal waveguide (800) with a mode coupling segment (820) comprising at least one bend (830) in the waveguide axis (810), wherein during operation the mode coupling segment (820) converts EM energy in a first guided mode to a second guided mode; (ii) providing EM energy in the first guided mode of the photonic crystal waveguide (800); and (iii) allowing the EM energy in the first guided mode to encounter the mode coupling segment to convert at least some of the EM energy in the first guided mode to EM energy in the second guided mode.

Electromagnetic mode conversion in photonic crystal multimode waveguides

Multi-cladding optical fibers to be used in the context of fiber amplifiers and fiber lasers are described herein. Embodiments of optical fibers include a rare-earth doped core into which the signal field is to be amplified. The doped core is surrounded by multiple claddings that guide the pump field to be absorbed by the reactive core material. The first cladding has a depressed refractive index to improve high-order mode bending losses without incurring significant fundamental mode bending losses.

Multi-cladding fiber

The present invention relates to a dispersion-shifted fiber having a structure for effectively lowering polarization-mode dispersion. This dispersion-shifted fiber is a single-mode optical fiber mainly composed of silica glass and has a zero-dispersion wavelength set within the range of at least 1.4 µm but not longer than 1.7 µm. In particular, at least the whole core region of the dispersion-shifted fiber contains fluorine.

Dispersion-shifted fiber

A reflector, a method of producing same and a method of creating high omnidirectional reflection for a predetermined range of frequencies of incident electromagnetic energy for any angle of incidence and any polarization. The reflector includes a structure with a surface and a refractive index variation along the direction perpendicular to the surface while remaining nearly uniform along the surface. The structure is configured such that i) a range of frequencies exists defining a photonic band gap for electromagnetic energy incident along the perpendicular direction of said surface, ii) a range of frequencies exists defining a photonic band gap for electromagnetic energy incident along a direction approximately 90° from the perpendicular direction of said surface, and iii) a range of frequencies exists which is common to both of said photonic band gaps. In an exemplary embodiment, the reflector is configured as a photonic crystal.

High omnidirectional reflector

A single mode optical waveguide fiber having a core refractive index profile of at least four segments (26, 28, 30, 36, 38, 40, 42) is disclosed. The main features of the core design are at least two non-adjacent core profile segments (26, 30, 36, 40) have positive Δ %; are, at least two non-adjacent segments (28, 32, 38, 42) have negative Δ %. The novel waveguide core design provides a single mode waveguide which is suitable for high rate, long regenerator spacing systems which incorporate optical amplifiers. The waveguide core structure also lends itself to the manufacture of dispersion managed waveguide fiber.

Large effective area single mode optical waveguide

A dispersion compensating single mode optical waveguide fiber designed to change the wavelength window of operation of a link from 1310 nm to 1550 nm. The dispersion compensating waveguide fiber is characterized by a core glass region refractive index profile comprised of at least three segments. The segment on the waveguide center has a positive relative refractive index. At least one segment, spaced apart from, the waveguide centerline has a negative relative refractive.

Dispersion compensating single mode waveguide

A single-mode optical waveguide fiber designed to limit power penalty due to four wave mixing and a method of making the waveguide is disclosed. Variations in properties, e.g., radius or refractive index, of the waveguide fiber core provide a total dispersion which varies along the length of the waveguide. The algebraic sum of products of length times total dispersion is controlled to a pre-selected value for each waveguide fiber which makes up a system link. Proper choice of total dispersion variation magnitude and sub-length results in a system link wherein a signal travels only short distances in waveguide portions having total dispersion near zero. However, the variation of the total dispersion provides a system link which has a pre-selected dispersive effect on the signal over a selected wavelength range. The dispersive effect on the signal can be chosen to be essentially zero. A number of techniques for fabricating DM fiber are also disclosed.

Dispersion managed optical waveguide

A single mode optical waveguide fiber having low, non-zero dispersion over a pre-selected wavelength range is disclosed. The refractive index profile of the core is characterized in that the core includes a plurality of distinct regions, each having an index profile, and a radius or width. By adjusting the index profile sizes and shapes of the plurality of core regions, a waveguide fiber may be made having a set of properties tailored for a high performance telecommunication system. In particular, dispersion slope can be maintained less than 0.05 ps/nm2 -km and absolute magnitude of total dispersion maintained in the range of 0.5 to 3.5 ps/nm-km over a pre-selected wavelength range. The zero dispersion wavelength is outside the pre-selected wavelength range and the cut off wavelength and mode field diameter are controlled to target values.

Controlled dispersion optical waveguide

Summary form only given. In summary, we have designed and fabricated single mode dispersion-shifted fibers, using the dual-ring index profile, with effective area as large as 90 /spl mu/m/sup 2/. The large effective area can greatly reduce the performance degradation caused by fiber nonlinearities for long-haul terrestrial and submarine applications. Furthermore, these fibers show lower bending losses than standard step-index single-mode fibers.

Large effective area dispersion-shifted fibers with dual-ring index profiles

The present invention provides an optical fiber, comprising a core having an alpha parameter in the range of approximately 2 to approximately 8, a maximum index percent difference between the core and a cladding in the range of approximately 0.3% to approximately 0.5% and a core diameter in the range of approximately 6.0 to approximately 16.0 μm and a cladding. The optical fiber has a bandwidth of at least approximately 0.6 GHz.km at 850 nm, and is configured for multimode operation at a wavelength less than 1300 nm and single mode operation at a wavelength of at least approximately 1300 nm. The fiber also has significantly reduced intermodal noise. The present invention also includes a method of designing such a fiber, a fiber optic system provided such a fiber and a method of operating a fiber optic system with such a fiber.

Yanming Liu

Papers

Dispersion compensating single mode waveguide

Dispersion managed optical waveguide

Controlled dispersion optical waveguide

Large effective area dispersion-shifted fibers with dual-ring index profiles

Broadband access optimized fiber and method of making