Abstract: A chromatic dispersion compensator whereby the amount of dispersion and the group delay time can be easily adjusted. A dispersion unit, a transmitting lens and a group delay generation unit are arranged along the optical axis of incident light. The dispersion unit separates the incident light into beams of respective different wavelengths. The transmitting lens is arranged across the optical paths of the beams of different wavelengths separated by the dispersion unit, and refracts the beams at different angles according to their respective incidence positions. The group delay generation unit is arranged across the optical paths of the beams of different wavelengths refracted by the transmitting lens, causes the beams to undergo propagation delay for periods corresponding to their respective incidence positions, and converges and emits the beams of different wavelengths. Consequently, the beams of different wavelengths are imparted group delay corresponding to the refracting angles of the transmitting lens.

Abstract: It is an object of the present invention to provide a control technique for reducing wavelength dependence of wavelength dispersion values and also for suppressing a change in wavelength transmission characteristic with a temperature variation or the like, in a VIPA-type wavelength dispersion compensator.

Abstract: A chromatic dispersion compensator whereby the amount of dispersion and the group delay time can be easily adjusted. A dispersion unit, a transmitting lens and a group delay generation unit are arranged along the optical axis of incident light. The dispersion unit separates the incident light into beams of respective different wavelengths. The transmitting lens is arranged across the optical paths of the beams of different wavelengths separated by the dispersion unit, and refracts the beams at different angles according to their respective incidence positions. The group delay generation unit is arranged across the optical paths of the beams of different wavelengths refracted by the transmitting lens, causes the beams to undergo propagation delay for periods corresponding to their respective incidence positions, and converges and emits the beams of different wavelengths. Consequently, the beams of different wavelengths are imparted group delay corresponding to the refracting angles of the transmitting lens.

Abstract: A transmission characteristics evaluation system can measure the dispersion tolerance and the insertion loss gradient tolerance at a high precision with reduced number of working steps for the measurement in evaluating the transmission characteristics of an optical module. The transmission characteristics evaluation system comprises an optical transmitting apparatus, an optical receiving apparatus for, and a pseudo transmission path apparatus interposed between the optical transmitting apparatus and the optical receiving apparatus. The pseudo transmission path apparatus has, in a pseudo manner, transmission characteristics of a transmission path to which the optical transmitting apparatus and the optical receiving apparatus are to be connected. The pseudo transmission path apparatus comprises a transmission characteristics setting section for setting transmission characteristics equivalent to the transmission characteristics that the transmission path can have, by controlling a mirror or an optical element.

Abstract: It is an object of the present invention to provide an optical component provided with a demultiplexing function capable of reducing an insertion loss and downsizing, and a wavelength dispersion compensator using such an optical component.

Abstract: A dispersion compensator comprising a VIPA is configured so as to reflect light with each wavelength at an angle varying depending on wavelength when the light is reflected off a mirror. When being coupled at the end of an input fiber, the light with each wavelength is coupled at a specific angle. If the light is coupled with the fiber at a specific angle, coupling efficiency degrades. Therefore, in this case, coupling loss increases. Light having a wavelength with high transmittance in the VIPA is coupled with the fiber at a large angle, while light with a low transmittance is efficiently coupled with the fiber at a small angle or no angle. In this way, the round-top wavelength characteristic of the VIPA can be leveled.

Abstract: An object of the invention is to provide a mirror fixing method capable of reducing stress distortion of a surface of a mirror which constitutes an optical system, with hardly deforming a surface shape of the mirror. To this end, the present mirror fixing method is characterized in that a mirror part including a base plate formed with a mirror on one face thereof, is provided with a boss on the other face of the base plate opposite to the face on which the mirror is formed, and only the boss is fixed, so that the mirror part excluding the boss is not in contact with other members.

Abstract: Input light is split by a PBS into orthogonal polarized waves. One of the polarized waves is reflected by a mirror HR, and input to a 7?/8 plate. The other is phase-controlled by a phase controller, and input to the 7?/8 plate. The respective light beams to which a phase bias is applied by the 7?/8 plate are input from a 2R mirror having reflectances that differ depending on a polarized wave to a GT resonator. The light beams output from the GT resonator again pass through the 7?/8 plate, inversely travel the original optical path, and enter the PBS. Then, the light beams are output from an output 1 or 2 depending on a polarized wave.

Abstract: A configuration is designed so as to comprise a light source that transmits light having a certain wavelength, a dispersion compensation module of passing characteristics variable type that compensates for the dispersion of light transmitted from the light source, and control means that control the passing characteristics of the dispersion compensation module so that the amount of the change in the intensity of light having passed through the dispersion compensation module is kept to a minimum. Due to this configuration, it is possible to make the passing characteristics of the dispersion compensation module follow the output wavelength of the light source for highly stable matching only by the stabilization of the output wavelength of the light source without stabilizing the respective wavelengths of both the light source and the dispersion compensation module independently of each other.

Abstract: A transmission characteristics evaluation system can measure the dispersion tolerance and the insertion loss gradient tolerance at a high precision with reduced number of working steps for the measurement in evaluating the transmission characteristics of an optical module. The transmission characteristics evaluation system comprises an optical transmitting apparatus, an optical receiving apparatus for, and a pseudo transmission path apparatus interposed between the optical transmitting apparatus and the optical receiving apparatus. The pseudo transmission path apparatus has, in a pseudo manner, transmission characteristics of a transmission path to which the optical transmitting apparatus and the optical receiving apparatus are to be connected. The pseudo transmission path apparatus comprises a transmission characteristics setting section for setting transmission characteristics equivalent to the transmission characteristics that the transmission path can have, by controlling a mirror or an optical element.

Abstract: Light input from a single-mode fiber is collected into linear light beams by a line focuser, and collected on a VIPA element. A light beam output from the VIPA element is made to pass through a space filter having a predetermined transmission loss characteristic, and focused on a mirror with a focusing lens. The light is reflected by the mirror, again passes through the space filter via the focusing lens, enters the VIPA element, and again enters the single-mode fiber via the line focuser. The insertion loss wavelength characteristic of the wavelength dispersion compensator using the VIPA element is optimized by being superimposed on the transmission loss characteristic of the space filter.

Abstract: A VIPA plate having a configuration where a translucent reflection film and a total reflection film are respectively arranged on one side and the other side of a transparent parallel plate can be used as a wavelength dispersion compensator by using a special mirror and a lens. However, the transparency characteristic of the wavelength dispersion compensator using such a VIPA plate is a periodical characteristic which is asymmetric with a central wavelength in a wavelength regime. Accordingly, not parallel light but converged or diverged light having angular dispersion is input to an etalon plate, so that a filter whose transparency characteristic is an asymmetric periodical characteristic which is reverse to the VIPA plate is configured for the central wavelength in the wavelength regime. With this filter, the transparency characteristic of the wavelength dispersion compensator using the VIPA plate is optimized.

Abstract: A cabinet provided with light input/output holes accommodates a VIPA optical element, a lens, a fixing material fixing the VIPA optical element. A temperature-controlled heater controls the temperature of and inside the cabinet. Both the light input and output holes of the cabinet are blocked by the fixing material and the lens, respectively, so that temperature inside the cabinet is not influenced by the outside air.

Abstract: It is an object of the present invention to provide a control technique for reducing wavelength dependence of wavelength dispersion values and also for suppressing a change in wavelength transmission characteristic with a temperature variation or the like, in a VIPA-type wavelength dispersion compensator.

Abstract: It is an object of the present invention to provide an optical component provided with a demultiplexing function capable of reducing an insertion loss and downsizing, and a wavelength dispersion compensator using such an optical component.

Abstract: A chromatic dispersion compensator whereby the amount of dispersion and the group delay time can be easily adjusted. A dispersion unit, a transmitting lens and a group delay generation unit are arranged along the optical axis of incident light. The dispersion unit separates the incident light into beams of respective different wavelengths. The transmitting lens is arranged across the optical paths of the beams of different wavelengths separated by the dispersion unit, and refracts the beams at different angles according to their respective incidence positions. The group delay generation unit is arranged across the optical paths of the beams of different wavelengths refracted by the transmitting lens, causes the beams to undergo propagation delay for periods corresponding to their respective incidence positions, and converges and emits the beams of different wavelengths. Consequently, the beams of different wavelengths are imparted group delay corresponding to the refracting angles of the transmitting lens.

Abstract: Light output from a single-mode fiber is output as parallel light from a two-core collimator, and input to a deflection prism. The parallel light output from the deflection prism is vertically input to an area approximately half that of a plane side of a line focus lens, passes through approximately half of the areas of the line focus lens, a VIPA element, and a light-gathering lens, and is illuminated on a free-form surface mirror, so that its wavelength dispersion is compensated. The light then passes through the remaining areas of the light-gathering lens, the VIPA element, the line focus lens, and the deflection prism, through which the light from the single-mode fiber does not pass through, and is input to the two-core collimator as parallel light. The parallel light input to the two-core collimator is converged by a collimate lens, and input to another single-mode fiber.

Abstract: An object of the invention is to provide a mirror fixing method capable of reducing stress distortion of a surface of a mirror which constitutes an optical system, with hardly deforming a surface shape of the mirror. To this end, the present mirror fixing method is characterized in that a mirror part including a base plate formed with a mirror on one face thereof, is provided with a boss on the other face of the base plate opposite to the face on which the mirror is formed, and only the boss is fixed, so that the mirror part excluding the boss is not in contact with other members.

Abstract: A stress correction film is applied to one side of a VIPA optical element provided with a multi-layer fully reflective film and an anti-reflective film on one surface of a transparent plate, and a semi-transparent multi-layer reflective film on the other surface, in order to adjust the unbalance between the respective stress of the multi-layer films on each surface. In other words, by applying a stress correction film, the unbalance between the respective stress of the multi-layer films on each surface of the VIPA optical element is corrected, and accordingly a VIPA optical element with low profile irregularity can be realized.

Abstract: A cabinet provided with light input/output holes accommodates a VIPA optical element, a lens, a fixing material fixing the VIPA optical element. A temperature-controlled heater controls the temperature of and inside the cabinet. Both the light input and output holes of the cabinet are blocked by the fixing material and the lens, respectively, so that temperature inside the cabinet is not influenced by the outside air.