Abstract: Embodiments of the present invention generally relate to fiber designs for wavelength tunable ultra-short pulse lasers. More specifically, embodiments of the present invention relate to systems incorporating fiber designs for higher order mode fibers capable of soliton self frequency shifting where a system comprises a first fiber for shifting the wavelength from a pump wavelength to a transfer wavelength and a second fiber for shifting the pulse from the transfer wavelength to an output wavelength. In one embodiment of the present invention, a wavelength tunable short pulse fiber laser system comprises: a pulse generator for providing a pulse having an input wavelength; a mode-converter; a first designed fiber for shifting the pulse from the input wavelength to a transfer wavelength; and a second designed fiber for shifting the pulse from the transfer wavelength to an output wavelength.

Abstract: A resistive heating element is used to fabricate a long-period grating mode converter. The resistive heating element creates a localized heating zone for creating an asymmetric perturbation at a periodic series of axial locations along the length of a segment of optical fiber that supports the propagation of both a symmetric mode and an asymmetric mode. In a further technique, a grating is written with an index contrast value that is higher than a selected optimum value. The heating element is then used to anneal the fiber segment so as to reduce the contrast value of the grating to the selected optimum value.

Abstract: Embodiments of the present invention are generally related to a fiber assembly, for example, in a chirped pulse amplification system, for all-fiber delivery of high energy femtosecond pulses. More specifically, embodiments of the present invention relate to a system and method for improving dispersion management when using hollow core photonic bandgap fibers for pulse compression. In one embodiment of the present invention, a fiber assembly comprises: an optical laser oscillator; a first fiber section for stretching the pulses from the laser oscillator, the first fiber section comprising a high order mode fiber; and a second fiber section for compressing the stretched pulses, connected to the first fiber section via a splice, the second fiber section comprising a hollow core photonic bandgap fiber; wherein the fiber assembly outputs a pulse compression at less than 200 fs.

Abstract: Embodiments of the present invention are generally related to embodiments of the present invention relate to a fiber stretchers module for use in the 1550 nm wavelength range. In one embodiment of the present invention, a fiber stretcher module for use in the 1550 nm wavelength range comprises a first fiber comprising a relative dispersion curve value of greater than about 0.0002 nm?2 and a dispersion value of less than about ?60 ps/(nm·km) at about 1550 nm, and a second fiber comprising a relative dispersion curve value of about zero and a relative dispersion slope value of about 0.003 nm?1 at about 1550 nm, wherein the fiber stretcher module comprises a collective relative dispersion slope of about 0.0413 nm?1 and a relative dispersion curve of about 0.00286 nm?2 at 1550 nm.

Abstract: Systems and methods for reducing modal group delay when transmitting a plurality of optical signals over a transmission line that supports a plurality of modes are disclosed. The modes are converted at a plurality of positions along the transmission line so the signals in the end have minimal group delay. The method comprises the steps of receiving N number of optical signals into a multimode fiber having at least N modes, transmitting each of N signals into a mode of the at least N modes of the multimode fiber, and converting each of the N modes into another of the N modes at N positions along the transmission line, such that the net modal group delay generated between the N signals along the transmission line is minimized.

Abstract: Embodiments of the present invention relate to a fiber design that achieves high nonlinearity, an effective index providing phase matching for an illustrative wavelength conversion process, and a low sensitivity to perturbations in fiber scaling. In one embodiment, a fiber comprises an inner core having an inner core radius and an inner core index, an outer core having an outer core radius and an outer core index, the outer core index being lower than the inner core index, an inner cladding, having an inner cladding radius and an inner cladding index, the inner cladding index being less than the outer core index, and an effective index of the fiber, the effective index being greater than the inner cladding index and less than the outer core index, wherein the fiber has a low perturbation sensitivity factor of dispersion to scaling less than about 20 ps/nm/km along the length of the fiber.

Abstract: A few-mode optical fiber comprises a core surrounded by a cladding, having a step index profile that is structured to support propagation of a plurality of desired signal-carrying modes, while suppressing undesired modes. The core and cladding are configured such that the undesired modes have respective effective indices that are close to, or less than, the cladding index such that the undesired modes are leaky modes. The index spacing between the desired mode having the lowest effective index and the leaky mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween.

Abstract: A dispersion-compensating system and a dispersion-compensating fiber have an improved figure of merit and effective area. The dispersion-compensating system comprises a bulk dispersion-compensating module for providing optical-domain bulk dispersion compensation for an optical signal transmission. Additionally, the system may further comprise residual dispersion compensation, which can be performed in the electrical domain following coherent detection of both amplitude and phase of an optical signal. The dispersion-compensating fiber comprises an up-doped core region; a down-doped trench; an up-doped ring; and an outer cladding, and is configured to have a high figure of merit (FOM).

Abstract: A stretcher fiber has a core region, inner trench region, ring region, outer trench region, and outer cladding region. The fiber regions are structured to provide the stretcher fiber with a relationship between dispersion and wavelength, such that the second and third derivatives of the stretcher fiber's propagation constant with respect to angular frequency have a shape and wavelength range matching those of a selected compressor module.

Abstract: Embodiments of the present invention are generally related to a fiber assembly, for example, in a chirped pulse amplification system, for all-fiber delivery of high energy femtosecond pulses. More specifically, embodiments of the present invention relate to a system and method for improving dispersion management when using hollow core photonic bandgap fibers for pulse compression. In one embodiment of the present invention, a fiber assembly comprises: an optical laser oscillator; a first fiber section for stretching the pulses from the laser oscillator, the first fiber section comprising a high order mode fiber; and a second fiber section for compressing the stretched pulses, connected to the first fiber section via a splice, the second fiber section comprising a hollow core photonic bandgap fiber; wherein the fiber assembly outputs a pulse compression at less than 200 fs.

Abstract: A stretcher fiber includes a core region, inner trench region, ring region, outer trench region, and outer cladding region. The core region has a radius r1, a refractive index n1, and a positive effective refractive index ?n1 with respect to an outer cladding region having an outer radius r0 and a refractive index n0, where ?n0 is equal to n1?n0. The inner trench region surrounds the core region and has an outer radius r2, a refractive index n2 less than n0, and a negative effective refractive index ?n2 equal to n2?n0. The ring region surrounds the trench region and has an outer radius r3, a refractive index n3 greater than n0, and a positive effective refractive index ?n3 equal to n3?n0. The outer trench region surrounds the ring region and has an outer radius r4, a refractive index n4 less than n0, and a negative effective refractive index ?n4 equal to n4?n0. The outer cladding region surrounds the outer trench region.

Abstract: A stretcher fiber has a core region, inner trench region, ring region, outer trench region, and outer cladding region. The fiber regions are structured to provide the stretcher fiber with a relationship between dispersion and wavelength, such that the second and third derivatives of the stretcher fiber's propagation constant with respect to angular frequency have a shape and wavelength range matching those of a selected compressor module.

Abstract: A stretcher fiber includes a core region, inner trench region, ring region, outer trench region, and outer cladding region. The core region has a radius r1, a refractive index n1, and a positive effective refractive index ?n1 with respect to an outer cladding region having an outer radius r0 and a refractive index no, where ?n0 is equal to n1?n0. The inner trench region surrounds the core region and has an outer radius r2, a refractive index n2 less than n0, and a negative effective refractive index ?n2 equal to n2?n0. The ring region surrounds the trench region and has an outer radius r3, a refractive index n3 greater than n0, and a positive effective refractive index ?n3 equal to n3?n0. The outer trench region surrounds the ring region and has an outer radius r4, a refractive index n4 less than n0, and a negative effective refractive index ?n4 equal to n4?n0. The outer cladding region surrounds the outer trench region.

Abstract: The present invention is directed to a universal channel dispersion compensating fiber (CDCF) for WDM channel compensation that provides essentially zero dispersion slope over the wide wavelength band used in state-of-the-art transmission systems. It allows compensation of a large number of channels using a single fiber design. The improved optical fiber of the invention exhibits a dispersion slope at 1550 nm: <0.02 ps/nm2-km, preferably <0.01 ps/nm2-km, and a maximum variation of dispersion per km over the S-, C-, and L- bands of preferably less than 2.0 ps. In a preferred embodiment, the index profile of these fibers comprises a simple three layer design, which includes an up-doped central core, surrounded by a down-doped trench region, further surrounded by an up-doped ring region.

Abstract: A technique is described for creating a localized modulation of an optical fiber's refractive index profile. A segment of optical fiber is loaded into a heating unit having a resistive heating element with a localized heating zone. A selected portion of the fiber segment is positioned within the heating zone, and the heating unit is used to create a refractive index modulation the selected fiber portion. The localized modulation is repeated along the length of the fiber segment to write a fiber grating. Also described is a resistive heating system for performing the described technique.

Abstract: The specification describes a universal channel dispersion compensating fiber (CDCF) for WDM channel compensation that provides essentially zero dispersion slope over the wide wavelength band used in state-of-the-art transmission systems. It allows compensation of a large number of channels using a single fiber design. The improved optical fiber of the invention exhibits a dispersion slope at 1550 nm: <0.02 ps/nm2-km, preferably <0.01 ps/nm2-km, and a maximum variation of dispersion per km over the S-, C-, and L-bands of preferably less than 2.0 ps. In a preferred embodiment, the index profile of these fibers comprises a simple three layer design, i.e. an up-doped central core, surrounded by a down-doped trench region, further surrounded by an up-doped ring region.

Abstract: A pumped Raman fiber optic amplifier includes two optical fibers whose lengths are determined so that the fibers exhibit dispersions of substantially equal magnitude and opposite sign at the wavelength of an input light signal. The fiber having the positive dispersion has a cylindrical core, an outer cladding, and a refractive index profile with respect to the outer cladding. The core has a diameter of between 3 and 6 microns (&mgr;m) and a difference (&Dgr;n) between the index of the core and the cladding is between 0.015 and 0.035. The index profile includes a trench region adjacent the circumference of the core, and the trench region has a width of between 1 and 4 &mgr;m and a &Dgr;n of between −0.005 and −0.015. The two fibers are slope matched so that the net dispersion of the amplifier remains substantially zero over a broad wavelength interval.

Abstract: The specification describes a universal channel dispersion compensating fiber (CDCF) for WDM channel compensation that provides essentially zero dispersion slope over the wide wavelength band used in state-of-the-art transmission systems. It allows compensation of a large number of channels using a single fiber design. The improved optical fiber of the invention exhibits a dispersion slope at 1550 nm: <0.02 ps/nm2-km, preferably <0.01 ps/nm2-km, and a maximum variation of dispersion per km over the S-, C-, and L-bands of preferably less than 2.0 Ps.

Abstract: A dispersion compensating fiber and module are described for controlling residual dispersion in a dispersion compensated system. The dispersion compensating fiber is designed with dispersion curve having an inflection point at a wavelength near the optical transmission operating wavelength region. The dispersion curve, having an inflection point near the operating wavelength region, produces a relative dispersion slope that closely matches the relative dispersion slope of the transmission fiber over a relatively wide bandwidth surrounding the operating wavelength region.

Abstract: A dispersion compensation module (DCM) for compensating dispersion of an optical fiber transmission link is provided. The optical fiber transmission link comprises a transmission fiber and the DCM. The DCM comprises at least first and second dispersion compensating fibers, DCF1 and DCF2, respectively. DCF1 and DCF2 each have a dispersion, D1 and D2, respectively, a dispersion slope, S1 and S2, respectively, and a relative dispersion slope, RDS1 and RDS2, respectively. The transmission fiber also has a dispersion, DTransFiber, a dispersion slope, STransFiber, and a relative dispersion slope, RDSTransFiber. DCF1 and DCF2 are selected based on their respective relative dispersion slopes, RDS1 and RDS2, respectively. DCF1 and DCF2 have particular, lengths, L1 and L2, respectively.