This invention generally relates to an optical filter for a fiber optic communication system. An optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

Power source for a dispersion compensation fiber optic system

There is provided a fiber optic transmission system, comprising: an optical signal source adapted to produce a frequency modulated signal; and a multi-ring resonator optical spectrum reshaper (OSR) adapted to convert the frequency modulated signal into a substantially amplitude modulated signal. And there is provided a method for transmitting an optical signal through a fiber comprising: producing a frequency modulated signal; passing the frequency modulated signal through a multi-ring resonator optical spectrum reshaper (OSR) so as to convert the frequency modulated signal into a substantially amplitude modulated signal; and passing the substantially amplitude modulated signal into the fiber.

Multi-ring resonator implementation of optical spectrum reshaper for chirp managed laser technology

This invention provides a system that combines a wavelength multiplexer with an FM discriminator for chirp reduction and wavelength locker in a filter to produce a wavelength division multiplexed signal with reduced chirp. A partially frequency modulation laser signal is converted into a substantially amplitude modulation laser signal. This conversion increases the extinction ratio of the input signal and further reduces the chirp. A wavelength division multiplexing (WDM) method is used for transmitting high capacity information through fiber optics systems where digital information is carried on separate wavelengths through the same fiber. Separate transmitters normally generate their respective signals that are transmitted at different wavelengths. These signals are then combined using a wavelength multiplexer to transmit the high capacity information through the fiber optic system. Various technologies can be used to multiplex the signals such as, for example, thin film filters, or arrayed waveguide gratings. In a WDM system, a wavelength locker may also be used that fixes the center wavelength of a transmitter to a reference. Wavelength lockers may include etalons or fiber gratings, either of which provides a reference wavelength. A control circuit typically compares the wavelength of the transmitter to the reference. An error signal adjusts the transmitter format wavelength by varying temperature or by other means to keep it locked to the reference wavelength.

Wavelength division multiplexing source using multifunctional filters

This invention generally relates to an optical filter for a fiber optic communication system. A coupled multi-cavity optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

High-speed transmission system comprising a coupled multi-cavity optical discriminator

This invention provides a flat dispersion frequency discriminator (FDFD) capable of having a substantially flat dispersion with either a positive or negative dispersion along the spectrum region of the discriminator. This way, a FDFD may not cause substantial distortion of the intensity patter of its output to minimize the occurrence distortion due to overshooting or undershooting of the intensity pattern depending on the relative spectral alignment of the laser output relative to the filter transmission.

Flat dispersion frequency discriminator (FDFD)

PROBLEM TO BE SOLVED: To solve the problems in the conventional methods that wavelength dispersion occurs in a signal transmitted on an optical fiber which brings about large disturbance in an optical communication, in which communication bit rate is >=10 Gbps, >=20 Gbps in particular and is not solved, even though various methods and elements for dispersion compensation have been proposed SOLUTION: A plurality of elements capable of performing dispersion compensation by utilizing the group velocity delay time-wavelength characteristics are serially connected to produce an optical dispersion compensation element, where bandwidth is large and the peak of group velocity delay time is large, and the tertiary dispersion compensation of an optical signal of a wide wavelength band, including an 1,460 to 1,640 nm wavelength band, is performed by using the optical dispersion compensation element

Optical communication method

PROBLEM TO BE SOLVED: To provide an optical phase multi-value modulation method of simpler configuration and an optical phase multi-value modulation device, and an error control method using the same. SOLUTION: When a ϕ degree is defined as a phase value and (n) as ≥3 and an integer below the number of phase shift modulators in the method for phase modulation of the laser beam from a laser beam source with a plurality of the phase modulators arranged in series, the phase modulation of 0° or 2ϕ° is performed in the first phase modulator and the phase modulation of 0° or 2 2 ϕ° is performed in the second phase modulator and generally, the phase modulation of 0° or 2 n ϕ° is performed in the n-th phase modulator. Also, the error detection or error control of each one bit is performed by making modulation and transmission with the same signals in the two modulators, receiving and decoding the signals on a reception side and confirming that their codes are the same. COPYRIGHT: (C)2004,JPO

Optical phase multi-value modulation method, optical phase multi-value modulating device, and error control method

PROBLEM TO BE SOLVED: To inexpensively provide an optical dispersion compensating element having such superior group velocity retardation time-wavelength characteristics that it can perform satisfactory dispersion compensation, particularly tertiary dispersion compensation even in a wide wavelength range in which a conventional element cannot be put to practical use as a miniature element easy to use, ensuring a small loss and having high reliability in a state suitable for mass production SOLUTION: The miniature highly stable optical dispersion compensating element ensuring a small loss and usable in a wide band is obtained by disposing multilayer films having dispersion compensating function on the opposite faces of a substrate capable of transmitting signal light in such a way that the planes of incidence confront each other Dispersion compensation is performed by reflecting signal light a plurality of times between the opposite multilayer films

Optical dispersion compensating element

PROBLEM TO BE SOLVED: To provide low-cost and small optical communications equipment and an optical communicating method, which can properly compensate for the secondary and tertiary dispersion of signal light different in dispersion levels for respective channel in optical communication. SOLUTION: Dispersion compensation is performed separately in a first dispersion compensating part performing it over a comparatively wide wavelength region and a second dispersion compensating part performing it for a comparatively narrow wavelength region. SMF is arranged in the first dispersion compensating part and an optical dispersion compensating element using a multilayer film is arranged in the second dispersion compensating part.

和朗菊池

Papers

Optical communication method

Optical phase multi-value modulation method, optical phase multi-value modulating device, and error control method

Optical dispersion compensating element

Optical communicating method and optical communications equipment using the same

和朗 菊池

Papers

Optical communication method

Optical phase multi-value modulation method, optical phase multi-value modulating device, and error control method

Optical dispersion compensating element

Optical communicating method and optical communications equipment using the same

和朗菊池