Abstract: Disclosed is a fiber amplifier system in which a gain fiber is operatively combined with a fiber optic coupler having first and second coupler optical fibers. The coupler fibers are fused together along a portion of their lengths to form a wavelength dependent coupling region whereby most of the light power of a wavelength .lambda..sub.S couples between them, and most of the light power of a wavelength .lambda..sub.P that is introduced into the first fiber remains in it. The mode field diameter of the first coupler fiber is substantially matched to that of the gain fiber and is smaller than that of the second coupler fiber. One end of the first coupler fiber is spliced to the gain fiber. The difference in mode field diameters between said couplers is sufficient create a difference in coupler fiber propagation constants in the coupling region which degrades the coupling of the .lambda..sub.S signal.

Abstract: An achromatic fiber optic coupler of the type wherein three single-mode optical fibers are fused together along a portion of the lengths thereof to form a coupling region. Each fiber includes a core and a cladding, the lowest refractive index of the fiber claddings being n.sub.2. The fibers are disposed in a triangular array in the coupling region. A matrix glass body of refractive index n.sub.3 surrounds the coupling region, n.sub.3 being lower than n.sub.2 by such an amount that the value of .DELTA..sub.2-3 is less than 0.125%, wherein .DELTA..sub.2-3 equals (n.sub.2.sup.2' -n.sub.3.sup.2)/2n.sub.2.sup.2.

Abstract: An achromatic fiber optic coupler of the type wherein a plurality of single-mode optical fibers, each having a core and a cladding, are fused together along a portion of the lengths thereof to form a coupling region. The propagation constants of the fibers are preferably equal; however if the fiber claddings have different refractive indices, the lowest cladding refractive index is n.sub.2. A matrix glass body of refractive index n.sub.3 surrounds the coupling region, n.sub.3 being lower than n.sub.2 by such an amount that the value of .DELTA..sub.2-3 is less than 0.125%, wherein .DELTA..sub.2-3 equals (n.sub.2.sup.2- n.sub.3.sup.2)2n.sub.2.sup.2.

Abstract: Disclosed is a fiber amplifier system in which a gain fiber is operatively combined with a fiber optic coupler having first and second coupler optical fibers. The coupler fibers are fused together along a portion of their lengths to form a wavelength dependent coupling region whereby most of the light power of a wavelength .lambda..sub.s couples between them, and most of the light power of a wavelength .lambda..sub.p that is introduced into the first fiber remains in it. The mode field diameter of the first coupler fiber is substantially matched to that of the gain fiber and is smaller than that of the second coupler fiber. One end of the first coupler fiber is spliced to the gain fiber. A transmission fiber is spliced to the second coupler fiber, and a laser diode introduces pumping light of wavelength .lambda..sub.p to the first coupler fiber. The fiber optic coupler preferably includes an elongated body of matrix glass through which the first and second coupler fibers extend.

Abstract: An optical two-way transmission-received communications system utilizing a coaxial coupler in place of a standard coupler, the optical system being capable of operation either in a single or multiple wavelength mode by designing the coupling region to have the proper length (i.e., either in 3dB or WDM operation), and further comprising a transmitter and a detector adjacent a coaxial coupler. The detector of the system is provided with a hole in its center in order to allow the transmitter access to the core waveguide of the coaxial coupler. The coaxial coupler may be formed from a rod in tube structure with a core waveguide extension adjacent the Tx/Rx and an integral pigtail on the opposite side of the coupler.

Abstract: This invention is drawn to heavy metal oxide glasses exhibiting high nonlinear susceptibility and infrared transmission consisting essentially, in weight percent, of 42-48% PbO, 33-44% Bi.sub.2 O.sub.3, 10-15% Ga.sub.2 O.sub.3, and up to 15% total of at least one member of the group consisting of up to 5% SiO.sub.2 and/or GeO.sub.2 and up to 15% Tl.sub.2 O. This invention also comprehends the fabrication of light guiding fibers from those glasses.

Abstract: This invention is drawn to heavy metal oxide glasses exhibiting high nonlinear susceptibility and infrared transmission consisting essentially, in weight percent, of 42-48% PbO, 33-44% Bi.sub.2 O.sub.3, 10-15% Ga.sub.2 O.sub.3, and up to 15% total of at least one member of the group consisting of up to 5% SiO.sub.2 and/or GeO.sub.2 and up to 15% Tl.sub.2 O. This invention also comprehends the fabrication of light guiding fibers from those glasses.

Abstract: An achromatic fiber optic coupler of the type wherein first and second single-mode optical fibers, each having a core and a cladding, are fused together along a portion of the lengths thereof to form a coupling region. A matrix glass of lower index than the fiber claddings surrounds the coupling region. The fiber diameters are smaller in the coupling region than in the remainder of the fibers. The refractive index n.sub.2 of the cladding of the first fiber is different from the refractive index n.sub.2 ' of the cladding of the second fiber, the difference between the refractive indices n.sub.2 and n.sub.2 ' being such that the coupler exhibits very little change in coupling ratio with wavelength over a band of wavelengths.

Abstract: Disclosed is a mode field modifier which can be used in a fiber-to-fiber connector or a source-to-fiber connector. In a downtaper-type mode field modifier embodiment, the modifier comprises a modifier core of refractive index n.sub.1 surrounded by first and second cladding layers having refractive indices n.sub.2 and n.sub.3, respectively. In an uptaper-type mode field modifier embodiment, the modifier comprises a modifier core of refractive index n.sub.1 surrounded by a cladding layer having a refractive index n.sub.2. The refractive indices are such that n.sub.1 >n.sub.2 >n.sub.3. In both embodiments, there is a nonadiabatic taper intermediate the ends of the mode field modifier, whereby a substantial amount of mode coupling occurs therein.