A functional panel, a method of manufacturing the same, and a terminal are disclosed. The functional panel includes a base substrate, at least one differential signal line group on the base substrate, where each differential signal line group of the at least one differential signal line group includes two signal lines and at least one ground line group on the base substrate and on the same side of the base substrate as the at least one differential signal line group. Each ground line group of the at least one ground line group includes two ground lines. Each ground line group corresponds to each differential signal line group one-to-one, and orthographic projections of the two ground lines in each ground line group on the base substrate are on both sides of an orthographic projection of a corresponding differential signal line group on the base substrate, and two ground lines in the ground line group are connected to a same reference ground.

An object of the present invention is to provide an optical transmission system capable of easily controlling a transmission capacity and an optical signal quality even if a MIMO equalizer is provided. The optical transmission system according to the present invention is provided with an N×M MIMO equalizer, includes receivers (N units) equal in number to the spatial multiplexing order L of an optical fiber, and changes the number M of the signal beams of light transmitted through the optical fiber in the range of the spatial multiplex order L or less. The adjustment of the number M of signal beams of light makes it possible to adjust a transmission capacity and a signal quality of the optical transmission system even after construction of the transmission line.

A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an LO norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.

A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an LO norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.

An apparatus and method to monitor a polarization change by inserting pilot signals in a transmission signal and converting the pilot signals in the receiving signal from a Jones space into a Stokes space. A velocity of a polarization change of the optical link is estimated by using the Stokes vectors of the pilot signals, thereby directly and accurately estimating the polarization change of the optical link. Moreover, estimation of the velocity of the polarization may be applicable where rotation of state of polarization and polarization-dependent loss coexist in an optical link.

An apparatus and method to monitor a polarization change by inserting pilot signals in a transmission signal and converting the pilot signals in the receiving signal from a Jones space into a Stokes space. A velocity of a polarization change of the optical link is estimated by using the Stokes vectors of the pilot signals, thereby directly and accurately estimating the polarization change of the optical link. Moreover, estimation of the velocity of the polarization may be applicable where rotation of state of polarization and polarization-dependent loss coexist in an optical link.

An adaptive equalizer (70) according to this invention includes an adaptive equalization filter (71) configured to adaptively compensate for a waveform distortion caused by a polarization fluctuation of a received signal (61) by updating a tap coefficient, a first tap coefficient updater (72) configured to calculate the tap coefficient according to the polarization fluctuation of the received signal (61) using a variable step size and update the tap coefficient of the adaptive equalization filter (71), a second tap coefficient updater (73) configured to calculate the tap coefficient according to the polarization fluctuation of the received signal (61) using a fixed step size μ.sub.0, a polarization state estimator (74) configured to estimate a polarization state of the received signal (61) using the tap coefficient calculated by the second tap coefficient updater (73), and a step size updater (75) configured to obtain the step size corresponding to the polarization state estimated by the polarization state estimator (74) and update the variable step size. According to this invention, it is possible to provide an adaptive equalizer that always implements stable followability to various SOP fluctuations.

An adaptive equalizer (70) according to this invention includes an adaptive equalization filter (71) configured to adaptively compensate for a waveform distortion caused by a polarization fluctuation of a received signal (61) by updating a tap coefficient, a first tap coefficient updater (72) configured to calculate the tap coefficient according to the polarization fluctuation of the received signal (61) using a variable step size and update the tap coefficient of the adaptive equalization filter (71), a second tap coefficient updater (73) configured to calculate the tap coefficient according to the polarization fluctuation of the received signal (61) using a fixed step size μ.sub.0, a polarization state estimator (74) configured to estimate a polarization state of the received signal (61) using the tap coefficient calculated by the second tap coefficient updater (73), and a step size updater (75) configured to obtain the step size corresponding to the polarization state estimated by the polarization state estimator (74) and update the variable step size. According to this invention, it is possible to provide an adaptive equalizer that always implements stable followability to various SOP fluctuations.

A polarization dependent loss (PDL) compensation device for an optical system can be configured to output a compensating PDL to at least partially cancel a PDL of the optical system. In certain embodiments, the device can include a first polarization controller configured to modify a state of polarization of an optical signal, a PDL emulator disposed upstream of the first polarization controller and configured to output the compensating PDL upstream of the first polarization controller, and a second polarization controller disposed upstream of the PDL emulator and configured to modify a state of polarization of the optical signal upstream of the PDL emulator.

A polarization dependent loss (PDL) compensation device for an optical system can be configured to output a compensating PDL to at least partially cancel a PDL of the optical system. In certain embodiments, the device can include a first polarization controller configured to modify a state of polarization of an optical signal, a PDL emulator disposed upstream of the first polarization controller and configured to output the compensating PDL upstream of the first polarization controller, and a second polarization controller disposed upstream of the PDL emulator and configured to modify a state of polarization of the optical signal upstream of the PDL emulator.