Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Toshiaki Okuno

Masayuki Nishimura

Eisuke Sasaoka

Masashi Onishi

Masaaki Hirano

Shigeru Tanaka

Motoki Kakui

Shinji Ishikawa

Tetsuya Nakanishi

Masao Tsukitani

Takatoshi Kato

Tomonori Kashiwada

Hiroshi Suganuma

Masakazu Shigehara

Makoto Katayama

Tomomi Sano

Hidehiko Takara

Satoki Kawanishi

Masato Tanaka

Tomohiko Kanie

Kunihiko Mori

Toru Iwashima

Fumiyoshi Ohkubo

Masa Tsukitani

Signal wavelengths &#x3bb;, &#x3bb;, &#x3bb;of signal light components multiplexed at signal multiplexing sectionsof multiplexing stationsinstalled on the input end side of an EDFAon an optical transmission lineare set such that the wavelength-dependent noise figure of EDFAsuccessively decreases from the signal wavelength &#x3bb;multiplexed at the signal multiplexing sectionclosest to the input end of EDFAto &#x3bb;and &#x3bb;. On the other hand, the transmission length of individual signal light component before being fed into the EDFAis the shortest in the signal light component at &#x3bb;and successively increases at &#x3bb;and &#x3bb;. Thus, the order of magnitude of input signal light power is the same as the order of highness of noise figure in EDFA, whereby fluctuations in S/N ratio in the resulting amplified light are reduced.

Channel allocation method for multi-channel optical transmission and optical transmission system utilizing the method

The present invention relates to a light source apparatus that has a base structure capable of generating SC light and further having a structure that enables the shaping of the spectral waveform of the SC light, power adjustment of the SC light, or adjustment of the frequency of repetition of the pulse train that contains the SC light. For example, a light source apparatus that enables shaping of spectral waveforms comprises a seed light source that emits seed light which is a pulse train or continuous light; an optical fiber that generates SC light from the seed light, and spectrum shaping means for completely or partially changing the spectral waveform of the SC light. The shaping of the spectral waveform changes the maximum power of the seed light by changing the optical coupling efficiency of the seed light source and optical fiber, for example, thereby suitably deforms the spectrum of the SC light.

Light source apparatus

Provided is a wavelength converter having a simple and low-cost structure. The wavelength converter generates converted light having a wavelength different from that of input light. The wavelength converter includes (1) a pump light source that outputs pump light, (2) an optical multiplexer that combines and outputs input light and the pump light, (3) a first optical fiber that receives and guides the input light and the pump light that have been combined and output by the optical multiplexer and generates converted light using a nonlinear optical phenomenon that occurs while the first optical fiber guides the input light and the pump light, the first optical fiber being coiled, and (4) zero-dispersion wavelength adjusting means that adjusts a zero-dispersion wavelength of the first optical fiber.

Wavelength converter

An optical fiber and a broadband light source that can generate SC light having a broader bandwidth. A broadband light sourceis equipped with a seed light sourceand an optical fiber. The seed light sourceoutputs light having a central wavelength in the wavelength range of 1500 nm to 1650 nm. The optical fiberoutputs supercontinuum light a result of input of the light output from the seed light source. The optical fiberwhich has a zero dispersion wavelength in the wavelength range of 1300 nm to 1500 nm and an effective area of 12 &#x3bc;mor less at the central wavelength, outputs supercontinuum light having a wavelength bandwidth expanded to 1000 nm or more.

Optical fiber and broadband light source

A broadband light source device that can generate supercontinuum light in a visible range and having a spectrum with a stable shape and high intensity is provided. The broadband light source device includes a diode-pumped solid-state laser light source that outputs seed light in response to being excited by a laser beam output from a semiconductor laser light source; a wavelength converter that receives the seed light to generate wavelength-converted light having a wavelength different from that of the seed light, and outputs the wavelength-converted light; and a nonlinear medium that receives the wavelength-converted light to generate supercontinuum light having a bandwidth of 100 nm or greater included in a wave band of 400 nm to 700 nm inclusive, and outputs the supercontinuum light.

Broadband light source device

In an optical amplifier according to the present invention, a change signal from a change signal source is fed into a light source or a drive circuit. The wavelength of light outputted from the light source is changed based on the change signal. The wavelength-changed output light from the light source is outputted as pumping light from a pumping light generator to be supplied backwardly via an optical multiplexer/demultiplexer into an optical fiber. Signal light is Raman-amplified in the optical fiber with the supply of the pumping light.

Light generator, optical amplifier, and optical communication system

A nonlinear optical signal-treating apparatus can suppress the distortion of pulse light to be inputted into an optical fiber to an allowable level or less. The apparatus comprises a pulse light source for outputting first pulse light, a first optical fiber, a second optical fiber that is spliced with the first optical fiber and has a mode-field diameter smaller than that of the first optical fiber, and a light-introducing system for inputting the first pulse light into the first optical fiber. The second optical fiber receives the first pulse light and generates second pulse light having a newly produced wavelength. The peak power ratio of the first pulse light outputted from the first optical fiber to that inputted into the first optical fiber and the pulse width ratio of the first pulse light outputted from the first optical fiber to that inputted into the first optical fiber are 0.5 to 1.5.

Nonlinear optical signal-treating apparatus

The invention relates to an optical transmission system which allows high quality transmission of signal light, and has a configuration that is suitable particularly for CWDM optical transmission. In the optical transmission system, signal channels outputted from non-temperature controlled direct modulation light sources are multiplexed by a multiplexer, transmitted through an optical fiber transmission line, and demultiplexed into a first wavelength band &#x39b;and second wavelength band &#x39b;by a demultiplexer. The signal channel group in the second wavelength band &#x39b;of which the absolute value of chromatic dispersion is large is dispersion-compensated for by a non-temperature controlled dispersion compensator. The chromatic dispersion of the signal channels in the second wavelength band &#x39b;after passing through the dispersion compensator is set to be negative over a temperature range of 0&#xb0; C. to 60&#xb0; C.

Optical transmission system

There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion &#x3b2;of fourth derivative &#x3b2;of propagation constant &#x3b2; with respect to angular frequency &#x3c9; at a mean zero dispersion wavelength &#x3bb;in an overall length is not more than 5&#xd7;10s/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than &#xb1;0.6 nm.

Optical fiber and optical device using the same

The wavelength converter comprises (1) an optical multiplexer for multiplexing an amplitude-modulated first light and reference light, which is continuous light having a wavelength different from the wavelength of the first light, (2) an optical fiber for propagating the multiplexed light therethrough to generate a third light by a non-linear optical phenomenon, and (3) an optical filter having a pass wavelength range set such that a pulse time width of the third light is 20% or more narrower than a pulse time width of the first light after the third light has passed through the optical filter, or (3') an optical filter having a pass wavelength range set such that a cross point of an eye pattern of the third light is lower than a cross point of an eye pattern of the first light after the third light has passed through the optical filter.

Method of wavelength conversion and wavelength converter

The present invention relates to a light source apparatus having a structure for stably supplying broadband pulsed light having a wavelength spectrum with an excellent flatness over a wide band. The light source apparatus employs, as a seed light source, a short-pulsed light source having such an excellent output pulse characteristic that the frequency bandwidth extending until the output pulse drops by 10 dB or 20 dB from a peak is 5 THz or more. The light source apparatus also includes a broadband light producing fiber having an optical characteristic suitable for combining with the short-pulsed light source. The broadband light producing fiber inputs pulsed light from the pulsed light source, and produces the broadband pulsed light by utilizing a nonlinear optical phenomenon. This structure yields broadband pulsed light having such a wavelength spectrum that a region whose power fluctuation is suppressed to 6 dB or less extends over 100 nm or more.

It is an object of the present invention to provide an optical transmission system in which multiple optical frequencies can be efficiently used and the change of the system can be easily made, and to provide an optical demultiplexer suitable for such optical transmission system. In an optical demultiplexer according to the present invention, signal light having a plurality of wavelength components arranged on a grid having predetermined frequency intervals is input from an input port thereof to be demultiplexed. The demultiplexed signal lights output from the output ports thereof have a plurality of wavelength components, respectively, and any three wavelength components, f, f, and f, that satisfy the following conditions: f&#x3c;f&#x3c;f; and f&#x2212;f&#x2266;N&#x394;f have the following relationship: 2f&#x2260;f+fwhere N represents an integer, and &#x394;f represents each of the predetermined frequency intervals.

Optical demultiplexer and optical transmission system

In the dispersion-compensating system of the present invention, a demultiplexer demultiplexes optical signals in a signal wavelength band of 1520 nm tonm propagating through a first common transmission line into C band (1520 nm to 1565 nm) and L band (1565 nm to 1620 nm). Then, the demultiplexer outputs the optical signals of C band into a first branched transmission line and the optical signals of L band into a second branched transmission line. A first dispersion-compensating device is provided on the first common transmission line and compensates for the dispersion in C and L bands. A second dispersion-compensating device is provided on the second branched transmission line and compensates for the dispersion in L band, which has not fully been compensated for by the first dispersion-compensating device. Hence, the dispersion of optical transmission line can fully be reduced in a wide signal light wavelength band.

Growing community of inventors

Yokohama, Japan

Toshiaki Okuno