Biomedical subjects

Junji Ohtsubo

Publications and source records attributed to Junji Ohtsubo.

3 recordsLinked to original sources

PubMed2003

Observation of the synchronization of chaos in mutually injected vertical-cavity surface-emitting semiconductor lasers.

Synchronization of chaotic oscillations was observed in mutually injected vertical-cavity surface-emitting lasers (VCSELs) in a low-frequency fluctuation regime. In the experiments, only one of the two polarization modes (x mode) showed synchronized oscillations, and the other polarization components (y mode) were synchronized as a result of the effect of anticorrelated oscillations that is a characteristic feature of VCSELs.

Journal Article↗

PubMed2003

Observation of low-frequency fluctuations in vertical-cavity surface-emitting lasers.

Low-frequency fluctuations, which are typical irregular oscillations in edge-emitting semiconductor lasers, are experimentally observed for the y-polarization mode (y is the direction along the optical axis of a laser material) in a vertical-cavity surface-emitting laser with optical feedback.

Journal Article↗

PubMed2002

Practical image encryption and decryption by phase-coding technique for optical security systems.

A method of image encryption and decryption is proposed for optical security systems. A phase-coded image to be encrypted together with a random phase pattern is Fourier transformed and the result of the complex-valued data is used as an encrypted pattern. The decryption is simply performed by an inverse-Fourier transform for the addition of the encrypted pattern and the Fourier transform of the random phase. The intensity of the inverse-Fourier transformed image gives the exact result forthe decryption. Further, the binarization of the encrypted pattern is performed for the easiness of the optical and electronic readout of the images, and it also gives rise to the enhancement of the degree of security for the encryption. The binary pattern is optimized by a statistical iteration technique and an excellent decryption image is obtained by the optimization.

Journal Article↗