Abstract: A wavelength selector to be used in WDM networks is provided. The wavelength selector is composed of a circulator, an arrayed waveguide grating (AWG), which is used for wavelength demultiplexing and multiplexing part, and an electro-optical (EO) switching part. The input light after the circulator is demultiplexed through the AWG part and each channel of the demultiplexed lights is modulated and reflected through the EO switching part which is formed as Michelson type interferometer with mirror parts returning the light to the AWG. The modulated and reflected light is multiplexed through the AWG and the direction is changed to the output through the circulator.

Abstract: The present invention relates to a multi-layer optical planar waveguide which is vertically coupled using multimode-interference couplers and to the method of manufacturing the same. The purpose of this invention is to increase the degree of integration on the multi-layer optical planar waveguide by applying the concept of via holes of the multi-layer printed circuit board (MLPCB) used in electronic circuits to the optical waveguide devices. According to the present invention, particularly, a multimode interference coupler of a stepped structure has the higher coupling ratio at relatively short length of interference than the usual multimode interference coupler. The present invention can implement a multimode interference coupler at a specialized spot while reducing evanescent field interference between the upper and lower optical waveguides out of the spot by separating the layers enough.

Abstract: There is disclosed a mode-locked optical fiber laser stabilizing apparatus for stabilizing the length of the optical fiber laser resonator by feedbacking the optical signals to the laser resonator, in the direction where the signal reflected by the optical fiber loop mirror is detected as an error signal to minimize the signal, and method thereof.

Abstract: A planar waveguide-type optical amplifier switch is disclosed. The switch is developed with the purpose of solving the problems that the conventional waveguide-type optical switch, which has been being used in the optical communication technique, has an optical loss and thereby requires an external optical amplifier which makes the whole devices not suitable for forming an integrated compact device. The disclosed switch performs switching function from the refractive index change in the optical waveguides induced by electrical or optical controls as well as amplifying function of the optical signal, when it passes through the waveguides, from use of optical waveguides formed of a fluorescence emitting material with an optical pumping and a wavelength division multiplexing (WDM) optical waveguide-type coupler.

Abstract: The present invention utilizes an amplified spontaneous emission (ASE) as a pumping source, thereby enhancing an amplification capability of a two-stage L-band EDFA. The two-stage L-band EDFA of the present invention includes a first amplifier and a second amplifier. The first amplifier is designed as a reflective amplifier, thereby re-amplifying a forward ASE by means of a gain medium. The first amplifier has a pumping LD, a WDM coupler, a first EDF and a Faraday rotating mirror. The second amplifier plays a role in amplifying an optical signal by utilizing the re-amplified forward ASE and the backward ASE as the pumping light. Here, the forward ASE and the backward ASE are transmitted to the second amplifier through an optical circulator. The second amplifier has a second EDF and an optical isolator.

Abstract: The present invention relates to a method of manufacturing a waveguide using an ion exchange process. The present invention controls the refractive index and the thickness of a surface layer on a glass substrate using an ion exchange process, forms the waveguide pattern on the surface layer by means of photolithography and etching process and coats with materials having the refractive index same to or lower than that of the glass substrate to form a cladding layer. Accordingly, the present invention can manufacture a planar waveguide, which is excellent in dimension control and reproducibility and has a sharp step wall.

Abstract: A high-speed wavelength channel selector has properties of relatively easy manufacturing and easy extension to multi-channel integration, and a high-speed space and wavelength multiplexed channel selector uses the high-speed wavelength channel selector. The high-speed wavelength channel selector is integrated with electro-optic waveguide switches of non-crystalline materials, such as electro-optic polymers or glasses, in the middle of a pair of wavelength multiplexer and demultiplexer and the high-speed space and wavelength multiplexed channel selector has the photonic integrated circuit-type composition of a space multiplexed channel selector containing M electro-optic waveguide switches and an M×1 channel combiner, the high-speed wavelength channel selector, optical amplifier and a high-speed wavelength converter.

Abstract: The present invention relates to a multi-channel wavelength division multiplexer/demultiplexer capable of efficiently coupling or separating wavelength multiplexed optical signals. The multi-channel wavelength division multiplexer/demultiplexer according to the present invention comprises a band splitting means for splitting the band of wavelength multiplexed optical signals (&lgr;1˜&lgr;n) into M bands, a demultiplexing means for separating each band split by the band splitting means into a plurality of single wavelength channels, and a multiplexing means for coupling the single wavelength channels separated by the demultiplexing means. Therefore, the present invention can significantly increase the number of available wavelength channels while minimizing optical loss of wavelength channels.

Abstract: An apparatus for measurement of an optical pulse shape intended to measure the temporal waveform of an ultrashort single optical pulse is disclosed. The present invention comprises a linearly chirped supercontinuum light source that is synchronized with an optical pulse to be measured; a nonlinear optical interferometer to transform the temporal waveform of an incident optical pulse into a spectrum using an incident light from said supercontinuum light source; and an optical spectrum analyzer to measure the wavelength of the light passing through the nonlinear interferometer so that it can measure the temporal waveform of a single optical pulse. The present invention employs the method that transforms the temporal waveform of an incident optical pulse into a spectrum and measures the wavelength using a linearly chirped supercontinuum light source, a nonlinear optical interferometer, and an optical spectrum analyzer.

Abstract: The present invention provides a tunable optical filtering system using fiber-optic polarimetric interferometer. The tunable optical filtering system using fiber-optic polarimetric interferometer in accordance with the present invention comprises a stabilization light source, a first polarization beam splitter, a first optical fiber node, a number of polarization maintaining optical fibers, a phase modulator, a stabilization electronics, a second optical fiber node, a second polarization beam splitter, and two wavelength division optical multiplexers. The stabilization light source supplies stabilization light. The first polarization beam splitter polarizes the stabilization light and the input light to be filtered and generates polarized light. The first optical fiber node connects the output of the first polarization beam splitter with polarization maintaining fibers with the angle of 45 degree between their birefringent axes and splits the polarized light.

Abstract: The present invention provides a demultiplexer for generating a constant four-wave-mixing beam without regard to an input polarization state using a dispersion-shifted fiber that is a nonlinear material with high refractive index. A number of parts in conventional demultiplexer implementations, which are sensitive to input polarization state has been replaced with optical fibers of high polarization mode dispersion.

Abstract: An optical fiber Mach-Zehnder interferometer optical filter is disclosed.

Abstract: The present invention discloses an all-optical wavelength converter using a semiconductor optical amplifier and a polarization interferometer. The all-optical wavelength converter using a semiconductor optical amplifier and a polarization interferometer including a wavelength converter which modulates a probe light into a inverting waveform to a signal light and outputs the modulated light by using cross gain modulation, a phenomenon that occurs while the signal light and the probe light pass together through an optical splitter/combiner, a semiconductor optical amplifier and a filter at the same time, a polarization interferometer which makes the probe light outputted from the wavelength converter and having the inverting waveform to the signal light undergo a double-refraction so that a predetermined time split occurs on it and provides a non-inverting wavelength conversion and suppresses the slow XGM components in the converted outputs due to the slow carrier recombination time.

Abstract: An improved multi-wavelength channel transmission filter, by which it is possible to selectively and simultaneously separate multiple wavelength channel signals without any optical time delays among, different wavelength channels, includes one optical circulator with four terminal ports, one polarization beam splitter (PBS), one half-wave plate, and a number of Brag, gratings formed in an optical waveguide for reflection of multi-wavelength channels by combining the wavelength characteristic of each Bragg grating which is determined in accordance with the grating structure.

Abstract: The present invention provides a multi-wavelength channel transmission-type optical filter that is capable of more narrowing the bandwidth of transmission wavelength in a transmission type optical filter using Mach-Zehnder interferometer. The multi-wavelength channel transmission-type optical filter including a first optical fiber coupler for dividing a broadband light source into two lights, an optical fiber length and optical fiber length controlling unit for controlling the gap of transmission wavelength in which each receives as inputs the above lights divided by the first optical fiber coupler, a second optical fiber coupler for outputting each of the above lights, which are passed through the optical fiber length controlling unit and the optical fiber length, and an optical isolator for narrowing the width of transmission wavelength by connecting the two outputs of the second optical fiber coupler, thereby improving a wavelength selecting characteristics.

Abstract: A laser structure for obtaining an optical pulse of a very short duration by using the benefit of a passive mode locking and for improving a repetition rate of an output optical pulse was described. In general, a passively mode-locked laser generates a short optical pulse than a active mode locked laser does, while it has difficulties in increasing the repetition rate of the output optical pulse because the repetition rate of the passively mode-locked laser is determined by the length of the resonator. In accordance with the present invention, a delayed optical path is added to the linear loop of a conventional figure-8 optical fiber laser. The propagation time difference .DELTA.T between the delayed optical path and undelayed short optical path is adjusted to a divisor of the round trip time, T, of the original resonator by properly adjusting the length of the delayed optical path. Thus, the repetition rate of the output optical pulse of the mode locked laser can be increased from 1/T Hz to 1/.DELTA.T Hz.

Abstract: A dual cavity laser having a positively mode-locked structure capable of double increasing the repetition rate of output light. The dual cavity laser includes an amplitude modulator to simultaneously generate two modulating signals with opposite phases. The dual cavity laser has a simply modified structure from that of the conventional single cavity laser to have two resonators, so that it can have a repetition rate corresponding to two times that of the single cavity laser. One of the resonators may have an adjusted optical property so as to obtain two kinds of output optical pulses with different optical properties.

Abstract: A pulsed semiconductor laser has a lower threshold current and a more stable pulse train. The structure includes a saturable absorber section has a quantum well structure for laser oscillation, a gain section, a phase control section, and a super structure grating-distributed Bragg reflector section. It uses an improved construction for overcoming problems of conventional pulsed semiconductor lasers. The improved structure includes five quantum well layers having thicknesses with respective spontaneous emission peak wavelengths of ".lambda.-2.delta.", ".lambda.+.delta.", ".lambda.+2.delta.", ".lambda.", ".lambda.-.delta." at room temperature from their upper section. .lambda. denotes the mean wavelength of the oscillating pulse laser, and .delta. denotes a fixed value less than 12 nm.