Abstract:
PURPOSE: To operate optical carrier extracting and reinserting equipment without relying upon polarization by making the equipment applicable to a wavelength division system by using a filter which can be adjusted finely for wavelength. CONSTITUTION: Various kinds of carriers existing at the branch 1e of a transmission line reach a fiber section after passing through the ports P1 and P3 of a circulator C1. A filter FP passes carriers having a wavelength and the carriers reach a receiver Rxi through a fiber 5. Carriers having the another wavelength are reflected by the filter FP and reach the output branch 1u of the transmission line through the ports P3 and P2 of the circulator C1. Similarly, carriers λwhich are transmitted from a transmitter and rely upon the input 3 of another circulator C2 pass through the filter FP in the reflecting direction and are inserted into a wavelength division multiplexing system at the output 1u of optical carrier extracting and reinserting equipment along a route (the ports P1' and P3' of the circulator C2, the fiber 5, and ports P3 and P2 of the circulator C1).
Abstract:
PROBLEM TO BE SOLVED: To efficiently use a transmission capacity. SOLUTION: In a ring network communication structure for communication with optical transmission lines 3A and 3B, plural nodes 2A...2E are mutually connected by at least first and second optical transmission lines 3A and 3B like optical fibers. A first wavelength λ1 is used for communication in one direction on the first transmission line 3A out of this pair of optical transmission lines to perform transmission in a ring network based on a WDN structure, and a second wavelength λ2 is used on the other optical transmission line 3B to perform communication in the opposite direction. If one of these connections gets faulty, nodes 2B and 2C adjacent to each other which cannot be connected are reconfigured, and the first wavelength λ1 is used on the second transmission line 3B and the second wavelength λ2 is used on the first transmission line 3A to continue the communication through another route given from the ring network. This structure is suitably applied to an SDH optical fiber ring network.
Abstract:
PROBLEM TO BE SOLVED: To provide method and equipment for measuring the nonlinear refractive index without requiring evaluation of maximum and minimum powers in spectrum. SOLUTION: A limited deformation optical pulse train having wavelength close to zero variance of a fiber 2 and a variable peak power causing self-phase modulation is fed through the fiber 2. Spectral extension of a signal leaving the fiber 2 is measured for several peak power values of pulse and the linear refractive index is obtained from the angular coefficient (inclination) of a line indicative of the spectral extension for peak power.
Abstract:
PURPOSE: To provide a wavelength selection optical switch which is simply and easily assembled by utilizing an equipment on the market and provided with really high wavelength selectivity for which the action of the equipment does not depend on polarized light since respective constituting elements do not depend on the polarized light further. CONSTITUTION: This two-input and two-output optical switch is provided with two optical circulators C1 and C2 with an input port and an output port which are the input/output of the switch and an optical band-pass filter FP placed between the two circulators C1 and C2 and a means capable of switching the carrier waves of a supplied wavelength so as to be reflected or transmitted and leading the carrier waves of the wavelength which enter the input port of one of the circulators C1 and C2 to the output port of the same circulator or the output port of the other circulator.
Abstract:
PURPOSE: To obtain deformation-limited ultra-short light, pulses, used for a high-bit-rate transmission system, by direct modulation of a semiconductor laser. CONSTITUTION: The ultra-short light pulses are obtained from pulses having pulse width exciting only the 1st peak of relaxation oscillation of the cavity of the laser 1, and the cavity is so adjusted that pulse parts overlapping with the inside of the cavity become long enough to cause structural interference. The pulses emitted by the laser 1 are passed through a fiber 8 having negative high dispersion to compensate phase effect by a chirp.