Abstract:
The lattice mismatching between a Ge layer and a Si layer is as large as about 4%. Thus, when the Ge layer is grown on the Si layer, penetration dislocation is introduced to cause leakage current at the p-i-n junction. Thereby, the photo-detection sensitivity is reduced, and the reliability of the element is also lowered. Further, in the connection with a Si waveguide, there are also problems of the reflection loss due to the difference in refractive index between Si and Ge, and of the absorption loss caused by a metal electrode. In order to solve said problems, according to the present invention, there is provided a vertical type pin-SiGe photodiode having a structure which is embedded in a groove formed in a part of a Si layer, in which a p-type or n-type doped layer is formed in a lower section of the groove, and in which a i-SiGe layer having a rectangular shape or a reverse tapered shape is formed on a layered structure formed by laminating a i-Si layer and a SiGe buffer layer on the lower section and the side wall of the groove. Further, in an optical connection section with a Si waveguide, impedance matching is effected by the layered structure composed of the i-Si layer and the SiGe buffer layer, and an upper metal layer is separated therefrom so that a poly-Si bridge structure is employed to electrically connect the upper metal layer therewith.
Abstract:
In a waveguide path coupling-type photodiode, a semiconductor light absorbing layer and an optical waveguide path core are adjacently arranged. An electrode formed of at least one layer is installed in a boundary part of the semiconductor light absorbing layer and the optical waveguide path core. The electrodes are arranged at an interval of (1/100)λ to λ [λ: wavelength of light transmitted through optical waveguide path core]. At least a part of the electrodes is embedded in the semiconductor light absorbing layer. Embedding depth from a surface of the semiconductor light absorbing layer is a value not more than λ/(2ns) [ns: refractive index of semiconductor light absorbing layer]. At least one layer of the electrode is constituted of a material which can surface plasmon-induced.
Abstract:
There is provided an optical device and an optical waveguide composed of a photonic crystal in which two optical waveguide modes that are orthogonal to a light propagation direction can be used, whereby design latitude is increased.In the optical waveguide device composed of a photonic crystal, in a dispersion relationship of the photonic crystal, light is propagated using a refractive index guide mode that is a minimum frequency optical waveguide mode. Alternatively, two optical waveguide modes that are orthogonal to light propagation direction are used, a linear defect waveguide mode is used for the first optical waveguide mode; and light is propagated in the second light guide mode by using a refractive index guide mode that is a minimum frequency optical waveguide mode in a dispersion relationship of the photonic crystal. Alternatively, in a dispersion relationship of the photonic crystal, light is propagated in two optical waveguide modes that are orthogonal to a light propagation direction using a refractive index guide mode that is a minimum frequency optical waveguide mode.
Abstract:
In an optical circuit including multi-dimensional photonic crystals, in which the optical circuit has a structure (33), such as a light emitting member or a light receiving member, having a natural resonance frequency, another structure (34) having a natural resonance frequency slightly differing from the natural resonance frequency of the structure (33) is arranged in the vicinity of the structure (33) to control the directivity of localization and propagation of an electromagnetic field, light emission and light reception in a spatial region including the above structures in the multi-dimensional photonic crystals, in order to permit functional operations to be realized.