Abstract: A compound refractive lens for neutrons is provided having a plurality of individual unit Fresnel lenses comprising a total of N in number. The unit lenses are aligned substantially along an axis, the i-th lens having a displacement ti orthogonal to the axis, with the axis located such that ∑ i = 1 N ⁢   ⁢ t i = 0. Each of the unit lenses comprises a lens material having a refractive index decrement &dgr;<1 at a wavelength &lgr;<200 Angstroms.

Abstract: A compound refractive lens for neutrons is provided having a plurality of individual unit Fresnel lenses comprising a total of N in number. The unit lenses are aligned substantially along an axis, the i-th lens having a displacement ti orthogonal to the axis, with the axis located such that 1 ∑ i = 1 N ⁢   ⁢ t i = 0.

Abstract: In accordance with the present invention, a compound refractive lens for focusing, collecting and collimating x-rays comprising N individual unit lenses numbered i=1 through N, with each unit lens substantially aligned along an axis such that the i-th lens has a displacement ti orthogonal to said axis, with said axis located such that the sum of the displacements ti equals zero, and wherein each of said unit lenses comprises a lens material having a refractive index decrement less than 1 at a wavelength less than 100 Angstroms.

Abstract: An all-optical fiber switch is implemented within a short Mach-Zehnder interferometer configuration. The Mach-Zehnder switch is constructed to have a high temperature stability so as to minimize temperature gradients and other thermal effects which result in undesirable instability at the output of the switch. The Mach-Zehnder switch of the preferred embodiment is advantageously less than 2 cm in length between couplers to be sufficiently short to be thermally stable, and full switching is accomplished by heavily doping one or both of the arms between the couplers so as to provide a highly nonlinear region within one or both of the arms. A pump input source is used to affect the propagation characteristics of one of the arms to control the output coupling ratio of the switch. Because of the high nonlinearity of the pump input arm, low pump powers can be used, thereby alleviating difficulties and high cost associated with high pump input powers.

Abstract: An optical mode coupling apparatus includes an Erbium-doped optical waveguide in which an optical signal at a signal wavelength propagates in a first spatial propagation mode and a second spatial propagation mode of the waveguide. The optical signal propagating in the waveguide has a beat length. The coupling apparatus includes a pump source of perturbational light signal at a perturbational wavelength that propagates in the waveguide in the first spatial propagation mode. The perturbational signal has a sufficient intensity distribution in the waveguide that it causes a perturbation of the effective refractive index of the first spatial propagation mode of the waveguide in accordance with the optical Kerr effect. The perturbation of the effective refractive index of the first spatial propagation mode of the optical waveguide causes a change in the differential phase delay in the optical signal propagating in the first and second spatial propagation modes.