Fumio Koyama

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We propose a novel design for multi-wavelength arrays of vertical cavity surface-emitting lasers (VCSELs) using high-contrast gratings (HCGs) as top mirrors. A range of VCSEL cavity wavelengths in excess of 100 nm is predicted by modifying only the period and duty-cycle of the high-contrast gratings, while leaving the epitaxial layer thickness unchanged.(More)
A hollow optical waveguide is proposed in which light can be confined in an air gap between a distributed Bragg reflecting (DBR) mirror and a high-index-contrast grating (HCG) mirror. Because of the combined effect of vertical (DBR) and lateral (HCG) periodicity, the proposed hollow waveguide shows a small modal birefringence on the order of 10 À4. In(More)
We propose a novel hollow-core slow light waveguide using high contrast grating (HCG). Light propagates in air along a path bounded by two HCG layers. A strong interaction between the light and the HCG leads to a large group index, and thus the slow light effect. Waveguide loss and group index can be optimized separately by tuning the HCG and waveguide(More)
A novel 8x8 optical phased array based on high-contrast grating (HCG) all-pass filters (APFs) is experimentally demonstrated with high speed beam steering. Highly efficient phase tuning is achieved by micro-electro-mechanical actuation of the HCG to tune the cavity length of the APFs. Using APF phase-shifters allows a large phase shift with an actuation(More)
Valley Marriott on the southern Californian coast. This is of course a special year for the Semiconductor Laser – a device that was first demonstrated half a century ago; and this has been marked by a number of excellent events this year looking back over that history. ISLC has a track record and a tradition as the leading international conference on(More)
—A tunable bandpass filter is constructed using pat-terned mirrors and a diffraction grating to serve as an optical equalizer. The frequency response of an intensity-modulated light source can be tailored by the passband profile of the equalizer to achieve a larger 3-dB bandwidth. We demonstrate that the 3-dB bandwidth of two LiNO 3 modulators is increased(More)