K. Hayashi

Bio: K. Hayashi is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Semiconductor laser theory & Far-infrared laser. The author has an hindex of 1, co-authored 1 publications receiving 77 citations.

Integrated twin-guide AlGaAs laser with multiheterostructure

Abstract: An integrated twin-guide (ITG) laser which has an active waveguide for laser oscillation and an external waveguide for the light output is proposed as an integrated-optics laser or as a new semiconductor laser, and its properties are investigated theoretically and experimentally. ITG lasers were constructed in the form of an AlGaAs multiheterostructure, and their preliminary characteristics were obtained with both optical pumping and current injection at room temperature. The end mirrors of the active waveguide were fabricated by a back-sputtering method. The axial mode selectivity was predicted by the analysis and observed experimentally.

Dynamic single-mode semiconductor lasers with a distributed reflector

Abstract: Recent progress in the dynamic single-mode (DSM) semiconductor lasers in the wavelength of 1.5-1.6\mu m are reviewed and the basic principle of DSM operation is given. Study of the DSM laser is originated for application to the wide-band optical-fiber communication in the lowest loss wavelength region of 1.5 to 1.65 μm. A DSM laser consists of a mode-selective resonator and a transverse-mode-controlled waveguide, such as the narrow-striped distributed-Bragg-reflector (DBR) laser, so as to maintain a fixed axial mode under the rapid direct modulation. The technology of monolithic integration for optical circuits is applied to realize some of DSM lasers. Structures, static and dynamic characteristics of lasing wavelength, output power, and reliability of the art DSM lasers are reviewed. The dynamic Spectral width of 0.3 nm, the output power of a few milliwatts, and the reliability over a few thousand hours are reported for experimental DSM lasers.

Frequency multiplexing light source with monolithically integrated distributed‐feedback diode lasers

Abstract: A frequency multiplexing light source is realized by monolithically integrating GaAs‐GaAlAs distributed‐feedback diode lasers with different grating periods and passive waveguides on a GaAs substrate. The lasers with wavelength separation of ∼20 A are modulated independently, and the output beams are obtained from a common launching waveguide.

Diode lasers coupled to external resonators

Abstract: This tutorial review is concerned with the properties of injection lasers operated with passive optical feedback. Thep-n junction laser characteristics relevant for operation in external cavities are summarized. The properties of diode lasers coupled to different types of external resonators are reviewed as well as experiments that incorporate passive feedback in monolithic integrated optical structures.

Efficient coupling in integrated twin-waveguide lasers using waveguide tapers

Abstract: We demonstrate a 1.55-/spl mu/m wavelength, InGaAsP-InP, twin-waveguide (TG) laser integrated with passive ridge waveguides using low-loss taper couplers. The lateral taper on the laser waveguide induces efficient resonant coupling of light between the active and passive layers. The device is fabricated using low-cost conventional photolithography and reactive ion etching of a TG structure grown by gas-source molecular beam epitaxy. This structure is suitable for integrating a variety of photonic devices without requiring epitaxial regrowth.