Abstract: Provided is a signal processing method including a step of acquiring a plurality of Stokes parameters related to polarization in which X polarization and Y polarization included in a dual-polarization phase-shift keying (DP-PSK) signal are defined as an x component and a y component, respectively, and a step of acquiring a two-dimensional constellation diagram by orthographically projecting coordinates defined by each of the Stokes parameters, in a Poincare sphere coordinate system, onto a plane including coordinates (0, 1, 0), (0, 0, 1), (0, ?1, 0) and (0, 0, ?1).

Abstract: An optical component of the present invention is compensated its optical dispersion, including third order dispersion, at low loss using optical dispersion compensating element comprising multi-layer film. In the optical component, an optical dispersion compensating element and a functional element are connected in series along an optical path.

Abstract: A phase modulation method and apparatus use a plurality of phase modulators disposed in series to phase-modulate light from a source laser. Modulation by the phase modulators is used to produce phase shifts in the optical signal, with modulation by the first phase modulator producing phase shifts of 0 degrees or 2&phgr; degrees, and modulation by the n-th phase modulator producing phase shifts of 0 degrees or 2n×&phgr; degrees. Here, &phgr; degrees is a predetermined phase level and n is an integer than two and not more than the number of phase modulators. The method is also used to detect and control transmission errors.

Abstract: In the past, the occurrence of wavelength dispersion in signals transmitted through optical fibers caused considerable problems in terms of communications at a communications bit rate of 10 Gbps or more, and particularly optical communications at 20 Gbps or more. In order to solve the problems, though various proposals of dispersion compensation method and element have been made for its compensation, any of which did not solve it.

Abstract: An optical component of the present invention is compensated its optical dispersion, including third order dispersion, at low loss using optical dispersion compensating element comprising multi-layer film. In the optical component, an optical dispersion compensating element and a functional element are connected in series along an optical path.

Abstract: This invention relates to an optical pulse reconstruction from sonogram. According to the present invention, there is provided a method for measuring an optical pulse which comprises: filtering an optical pulse to obtain a frequency-filtered pulse, a transfer or window function for said frequency filtering being given; measuring a sonogram, which is defined as the intensity waveform of said frequency-filtered pulse, to obtain a measured sonogram; and reconstructing said optical pulse by using said measured sonogram and said transfer or window function. The present invention also provides a formula for retrieving the amplitude and phase of an optical pulse from its sonogram. When the transfer function of the frequency filter is known, the pulse amplitude and phase are completely retrieved from the sonogram without iterative calculations by derived formula.

Abstract: A completely thin-film coupled three-cavity dispersion compensation element enables dispersion compensation over wider bandwidths then similar elements having fewer coupled cavities. By cascading these dispersion compensation elements even greater compensation bandwidths can be obtained, thereby further increasing the merit and usefulness of this device.

Abstract: This invention, a composite dispersion compensation structure, made up of at least two dispersion compensation elements in an opposing arrangement, and at least one reflection element, can provide low cost dispersion compensation over a wide bandwidth by utilizing multiple reflections.

Abstract: This invention, a composite dispersion compensation structure made up of at least two dispersion compensation elements in an opposing arrangement, can provide low cost dispersion compensation over a wide bandwidth by utilizing multiple reflections.