Nippon Telegraph and Telephone Corporation

School Juridical Person Kitasato Institute

Fumiyoshi Kano

Hiroyuki Furukawa

Takeo Miyazawa

Ryoko Yoshimura

Kimiya Shimizu

Kohji Ohbayashi

Motoi Nakanishi

Takuji Amano

Hideaki Hiro-Oka

DongHak Choi

Hiroyuki Ishii

Toshiaki Tamamura

Yoshikuni

Yuichi Tohmori

An OCT technique that permits tomographic observation of biological body parts that are difficult to restrain, and also provides a tomographic observation technique for the observation of a constrainable part that does not require constraint and thus removes a burden on the biological body. A wavelength-tunable light generator (wavelength-tunable light source) is employed as the light source of the optical coherence tomography device. The wavelength-tunable light generator has a wave number tunable range width of at least 4.7&#xd7;10&#x3bc;mand an emitted-light frequency width of no more than 13 GHz, for example, and is capable of changing the wave number stepwise at wave number intervals of no more than 3.1&#xd7;10&#x3bc;mand time intervals of no more than 530 &#x3bc;s.

Wavelength-tunable light generator and optical coherence tomography device

The present invention provides an OCT technique that permits tomographic observation of a biological body parts that is difficult to restrain and also provides a tomographic observation technique for the observation of a constrainable part that does not require constraint and remove the burden from biological body. A wavelength-tunable light generator (wavelength-tunable light source) is employed as the light source of the optical coherence tomography device. The wavelength-tunable light generator has a wave number tunable range width of at least 4.7&#xd7;10&#x3bc;mand an emitted-light frequency width of no more than 13 GHz, for example, and includes means capable of changing the wave number stepwise at wave number intervals of no more than 3.1&#xd7;10&#x3bc;mand time intervals of no more than 530 &#x3bc;s.

The distributed reflector includes a substrate and at least one optical waveguide formed on the substrate and having a refractive index larger than the substrate and at least one optical confinement layer having a refractive index smaller than the optical waveguide layer. A diffractive grating is formed in at least one layer constituting the optical waveguide. The diffractive grating has a structure of which at least one parameter defining optical reflectivity varies depending on its position, and is formed continuously for at least two periods, the period being approximately defined by the length of repeating unit region. The parameter may be pitch, coupling coefficient, bandgap composition, phase shift, etc. The semiconductor laser includes the distributed reflector which may be of a distributed reflector type or distributed feed back type and has distributed reflector regions and a phase adjustment region. Application of current or voltage to the refractive index of the active region or inactive region in which a diffractive grating is present or absent adjusts the refractive index thereof and enables coarse and fine adjustment of lasing wavelength.

Distributed reflector and wavelength-tunable semiconductor laser

Growing community of inventors

Kanagawa, Japan

Fumiyoshi Kano