Matsushita Electric Industrial Co., Ltd.

Jingo Adachi

Akihiro Itoh

Shinichi Wakabayashi

An encoder according to the present invention is an encoder for encoding an optical wavelength-multiplexed signal compliant with optical CDMA into a code having a code pattern, including: L optical fibersand(where L is an integer equal to or greater than two) each having a plurality of gratingsto; and a circulatorfor coupling the plurality of optical fibersand. The code pattern contains time bins tto t. A plurality of wavelengths &#x3bb;and &#x3bb;are assigned to the time bin t. If a sum of an optical path difference in each optical fiber from the grating which reflects the optical signal of the wavelength &#x3bb;to the grating which reflects the optical signal of the wavelength &#x3bb;is calculated for all of the optical fibersand, the sum equals zero.

Encoder/decoder for optical CDMA

There is provided an apparatus for performing, by optical code division multiplex access, at least one of encoding and decoding of wavelength-division-multiplexed light. The apparatus includes: an optical input/output sectionfor handling input/output of the wavelength-division-multiplexed light; and N fiber gratings (where N is an integer equal to or greater than two)to, which are in a series connection to the optical input/output section. Each of the N fiber gratings has a sampled grating structure having an alternating array of first regions (toto; andto) which provide a refractive index modulation with a relatively large amplitude and second regions () which provide a refractive index modulation with a relatively small amplitude, the first and second regions being disposed with a constant period P. Each sampled grating structure defines a plurality of reflection wavelength bands which are replicated with a period that is equal to the interval (&#x394;T) between the central wavelengths of wavelength bands contained in the wavelength-division-multiplexed light. The central values of the respective reflection wavelength bands differ from one fiber grating to another at least during operation.

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Osaka, Japan

Jingo Adachi