Kazuaki Kiyota

Various low group velocity effects in photonic crystal line defect waveguides and their demonstration by laser oscillation

We investigated propagating modes in a two-dimensional photonic crystal slab waveguide with a line defect narrower than a single line missing hole structure from the low group velocity point of view. These modes showed low group velocities not due to the conventional distributed feedback (DFB) between a forward and a backward mode with the same lateral field distribution, but due to a DFB between modes with different lateral field distribution or property of a start point of a photonic-band-gap-guided mode. These low group velocities of over 40 were demonstrated as a Fabry-Perot lasing oscillation due to gain enhancement.

Optical absorption coefficient of carbon-doped GaAs epitaxial layer by means of propagation -loss measurement of waveguide for long wavelength VCSEL

The optical absorption coefficient (α) for carbon-doped GaAs epitaxial layer by CBr<inf>4</inf> with doping range from 10¹⁸ to 10²⁰ cm⁻³ was measured for the first time. Obtained α<inf>GaAs:C</inf> was 2-times larger than α<inf>GaAs:Zn</inf> at 1300nm.

Characterization of Photonic Crystal Waveguide for SOA Operation

We investigated the GaInAsP photonic crystal active waveguide integrated with passive I/O waveguides for SOA operation. Light propagation by the photonic band and its control by photopumping were confirmed in the experiment.

1550 nm AlGaInAs/InP widely tunable BH laser based on arrayed DFB

We have fabricated high performance 1550nm both solitary lasers and the 12-channel arrayed DFB/SOA integrated widely tunable lasers with buried-heterostructure configuration in the AlGaInAs/InP system. An output power of 100mW was obtained for tunable lasers at 20°C.

Measurement of Absorption Coefficient of Carbon-Doped GaAs

The optical absorption coefficients of carbon-doped GaAs in a wide range of doping concentrations (1018 to 1020 cm-3) were measured by waveguide propagation loss and wafer measurements. Experimental data indicate twofold higher absorption coefficients for C-doped GaAs than for Zn-doped GaAs at a wavelength of 1300 nm.

Thermal lens effect on single-transverse-mode stability of proton-implanted photonic-crystal vertical-cavity surface-emitting lasers

Thermal lens effect on single-transverse-mode stability of proton-implanted photonic-crystal vertical-cavity surface-emitting lasers is studied. Theoretical and experimental demonstration of the trade-off between the single-mode stability and low loss. Single-mode stability with a smaller lattice constant is also discussed.

Demonstration of various low group velocity effects in photonic crystal line defect waveguides by laser oscillation

In this work, waveguide modes were investigated in a two-dimensional photonic crystal slab, which lie above light line, from the point of view of the low group velocity. Low group velocity effects other than usual distributed feedback (DFB) were demonstrated as Fabry-Perot lasing oscillation in the short cavity length of 70 /spl mu/m.