Oki Electric Industry Co., Ltd.

Shuko Kobayashi

Kensuke Sasaki

Akihiko Nishiki

Satoko Kutsuzawa

An optical pulse time spreading apparatus wherein an optical splitter divides an input optical pulse into first to U-th input optical pulses; first to U-th optical pulse time spreaders respectively have the first to U-th input optical pulses input thereto and output first to U-th chip pulse sequences each consisting of N chip pulses from a first to an N-th chip pulse arranged in order on a time axis into which the input optical pulse is time-spread; and an interval between adjacent ones of unit FBGs arranged in a p-th optical pulse time spreader and a Bragg reflection wavelength of the unit FBGs in the p-th optical pulse time spreader are set such that spectra of the first to U-th chip pulse sequences are different from each other.

Encoding-decoding method, optical pulse time spreading apparatus, optical add-drop-multiplexer, and optical communication system

An optical code division multiplexing signal generator provided with an optical pulse light source, a first encoder to an Nencoder, a first optical modulator to an Noptical modulator, and a first optical circulator to an Noptical circulator. The first optical circulator inputs an input optical pulse train to a first encoder, and inputs a first encoded optical pulse train output by Bragg reflection from the first encoder to the first optical modulator. The koptical circulator inputs an input (k&#x2212;1)optical pulse train which has passed through the (k&#x2212;1)encoder to a kencoder, and inputs a kencoded optical pulse train output by Bragg reflection from the kencoder to the koptical modulator. Herein k takes all integers from 2 to N, and N is a positive integer of 2 or more.

Optical code division multiplex signal generator

An FBG system with lower power supplied to a temperature controller, while allowing for precise temperature control of an FBG grating. The FBG system includes a high temperature FBG-mounting structure and a low temperature FBG-mounting structure, and a housing containing them. The high temperature FBG-mounting structure includes an FBG module and a thermo module. The temperature of the FBG in the FBG module may be made higher than the environmental temperature by supplying heat from a heat-conducting portion to the thermo module. The low temperature FBG-mounting structure includes an FBG module and a thermo module. The temperature of the FBG in the latter FBG module may be made lower than the environmental temperature by supplying heat from the latter thermo module to the heat-conducting portion. The FBG-mounting structures are provided in parallel on the inner bottom surface of the heat-conducting portion, part of the housing.

Fiber Bragg grating system having a thermo module for supplying or absorbing heat to or from an FBG module

An optical pulse time spreader which can generate a chip pulse string of which intensity is equalized. The reflectances R, Rand Rof the first, second and k-th (k is an integer which satisfies 3&#x2266;k&#x2266;J) unit FBG are given by the following formulae respectively.(constant) &#x2003;&#x2003;(a)/(1&#x2212;)&#x2003;&#x2003;(b)=()/{(1&#x2212;)&#xb7;(1&#x2212;). . . (1&#x2212;)} &#x2003;&#x2003;(c-1)=()/{(1&#x2212;)&#xb7;(1&#x2212;). . . (1&#x2212;)} &#x2003;&#x2003;(c-2) Here Pis an arbitrary constant, and Pis an intensity of a triple reflection chip pulse which is output for the k-th time. The formulae (c-1) and (c-2) are the reflectance of the k-th unit diffraction grating when the phase difference between the single reflection chip pulse, which is output for the k-th time, and the triple reflection chip pulse, which is output for the k-th time, is 0 and &#x3c0; respectively.

Optical pulse time spreader

An optical code division multiplexing communication method includes the steps of: producing a multi-wavelength optical pulse train from wavelength multiplexing pulse; transmitting the multi-wavelength optical pulse train through a transmission line using a time-spreading/wavelength-hopping method; decoding wavelength multiplexing pulse from the multi-wavelength optical pulse train transmitted through the transmission line; compensating delay time differences between individual optical pulses of the multi-wavelength optical pulse train, the delay time differences occurring in the step of transmitting the multi-wavelength optical pulse train through the transmission line; and compensating optical pulse spread in a time direction, which occurs in each of the optical pulses of the multi-wavelength optical pulse train in the step of transmitting the multi-wavelength optical pulse train through the transmission line.

Optical code division multiplexing communication method and system

An object of the present invention is to adjust the operating wavelength of a decoder, in order to coordinate the operating characteristics of an encoder and the decoder. To this end, an optical code division multiplex transmission device of the present invention comprises a second SSFBG in the decoder, and has a mechanism to perform adjustment (phase adjustment step) of the fixation portion interval L which is the interval between a first and second fixation portions fixing in place the second SSFBG, such that the extent of the eye opening of optical pulses output from the second SSFBG is maximum. The extent of the eye opening is measured using a correlation waveform monitor, and the measurement data is sent to the wavelength control portion. A signal is sent from the wavelength control portion to the movement control portion to set the fixation portion interval L, based on data relating to the extent of the eye opening sent from the correlation waveform monitor.

Optical code division multiplex transmission method and optical code division multiplex transmission device

The present invention is an SSFBG with which there are few restrictions on the code that can be set and the overall length of which is short. This SSFBG has four unit FBGs the Bragg reflection wavelengths of which are &#x3bb;, &#x3bb;, &#x3bb;, and &#x3bb;disposed with a part where the unit FBGs overlap one another in the waveguide direction of the optical fiber. The left end of the horizontal axis corresponds to the position of the I/O terminal of the SSFBG and the right end of the horizontal axis corresponds to the terminal on the opposite side from the I/O terminal of the SSFBG. The Bragg reflection wavelengths &#x3bb;, &#x3bb;, &#x3bb;, and &#x3bb;of the four unit FBGs are &#x3bb;=1543.28 nm, &#x3bb;=1543.60 nm, &#x3bb;=1543.92 nm, and &#x3bb;=1544.24 nm respectively. Codes (&#x3bb;, &#x3bb;, &#x3bb;, and &#x3bb;) used in the time-spreading/wavelength hopping system are established for the SSFBG by disposing the four unit FBGs at equal intervals such that the interval therebetween is 12.8 mm.

Optical pulse time spreading device

A wavelength tuning device of the invention tunes the reflected wavelength of a fiber Bragg grating, and includes: an optical fiber () in which a fiber Bragg grating () is formed; a base member () to which the optical fiber (is fixed; a first temperature sensor () that detects a temperature of the base member (); a thermo-module () that adjust the temperature of the base member () such that the temperature detected by the first temperature sensor () is maintained at a desired temperature; a second temperature sensor () that detects an external temperature of the wavelength tuning device; and a temperature controller () that controls the thermo-module () such that the temperature of the base member () is maintained at the desired temperature based on the external temperature detected by the second temperature sensor ().

Wavelength tuning device and wavelength tuning method

There is provided a fiber Bragg grating devise comprising an FBG mount that is constituted by sequentially stacking a temperature control plate, a base plate, and a mounting plate, and an SSFBG in which a plurality of FBG units of the same constitution and a plurality of phase modulation portions are alternately formed in the same optical fiber. The temperature control plate is constituted by a thermo module and a heat-insulating member. The base plate is fixed in contact with the upper face of the temperature control plate and the mounting plate is in contact with the upper face of the base plate in a state where the mounting plate is able to glide over the upper face of the base plate. The SSFBG is fixed to contact an FBG contact portion that is established on the upper face of the mounting plate. The phase modulation portions are formed to be capable of expanding and contracting and, as a result of the expansion and contraction of the phase modulation portions, the phase of the carrier wave of the optical pulse signal that is propagated by the phase modulation portions can be changed.

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Kanagawa, Japan

Shuko Kobayashi