As a template for scaled Ge-FinFETs, anisotropic wet etching was applied to obtain narrow Ge-fins with smooth sidewalls. It was found that Ge (110) facets were formed with a higher pH APM etchant. 100nm-width Ge-fin structures were slimmed to approximately 30nm by the APM etching. Moreover, LWF (Line Width Fluctuation) values of the Ge-fin were reduced by the emergence of (110) facets due to the lower etching rate on {110} surfaces. These results suggest that the wet etching process is applicable to future high-performance Ge-FinFETs.

Optical losses in pillar microcavities have been measured directly by means of microreflectance spectroscopy. It was shown that optical losses of the cavities larger than about 3 μm were constant irrespective of the diameters. The lasing thresholds were also measured, and they were proportional to the cavity volume. This result is consistent with the measured constant optical losses. A drastic increase in optical losses has been observed when reducing the cavity diameters below 2 μm. The scattering losses due to sidewall roughness were considered mainly responsible for the optical losses.

High-efficiency laser oscillations by means of resonant optical pumping were observed in a planar microcavity laser with a single quantum well active layer. The threshold excitation power density was 19 W/cm2, and the differential energy conversion efficiency was 14%. This high efficiency is attributed to the absorption enhancement effect in the microcavity. Output power saturation was also observed in the input–output curve when the excitation wavelength was close to the band-edge wavelength. This saturation is considered to result from the resonance wavelength varying with the excitation intensity.

The self-starting fiber ring laser structure (FRL) employing additive pulse modelocking (APM)' is an important technique for subpicosecond pulse generation. In this paper, a mathematical model is developed to investigate theoretically the self-starting conditions of the FRL and their relationship to practical design parameters for the first time.The FRL configuration discussed below is similar to that in Ref. l. Let U, and U, be the normalized slow varying envelops for the x-and ypolarizations. Following the approach of G. P. Agrawal: the evolutions of both polarizations in the regular optical fiber and erbium-doped fiber (EDF) are described by e uations (1) and (2) respectively in below?

No abstract