Abstract:
A downsized, low-power electro-optical modulator that achieves reducing both of the additional resistance in the modulation portion and the optical loss each caused by electrodes at the same time is provided. The electro-optical modulator includes a rib waveguide formed by stacking a second semiconductor layer 9 having a different conductivity type from a first semiconductor layer 8 on the first semiconductor layer 8 via a dielectric film 11, and the semiconductor layers 8 and 9 are connectable to an external terminal via highly-doped portions 4 and 10, respectively. In a region in the vicinity of contact surfaces of the semiconductor layers 8 and 9 with the dielectric film 11, a free carrier is accumulated, removed, or inverted by an electrical signal from the external terminal, and whereby a concentration of the free carrier in an electric field region of an optical signal is modulated, so that a phase of the optical signal can be modulated. At least one of the semiconductor layers 8 and 9 is wider than the stacked portion. At least one of the highly-doped portions 4 and 10 is formed outside the stacked portion.
Abstract:
An optical modulator according to the present invention is configured at least by a semiconductor layer subjected to a doping process so as to exhibit a first conductivity type, and a semiconductor layer subjected to a doping process so as to exhibit a second conductivity type. Further, in the optical modulator, at least the first conductivity type semiconductor layer, a dielectric layer, the second conductivity type semiconductor layer, and a transparent electrode optically transparent in at least a near-infrared wavelength region are laminated in order.
Abstract:
An optical modulation structure includes a lower cladding layer (102), a first silicon layer (103) integrally formed from silicon of a first conductivity type on the lower cladding layer (102) while including a core (104) and slab regions (105) arranged on both sides of the core (104) and connected to the core, a concave portion (104a) formed in an upper surface of the core (104), and a second silicon layer (109) of a second conductivity type formed on a dielectric layer (108) in the concave portion (104a) so as to fill the concave portion (104a).
Abstract:
In an electro-optic device, a stack structure including a first silicon layer of a first conductivity type and a second silicon layer of a second conductivity type has a rib waveguide shape so as to form an optical confinement area, and a slab portion of a rib waveguide includes an area to which a metal electrode is connected. The slab portion in the area to which the metal electrode is connected is thicker than a surrounding slab portion. The area to which the metal electrode is connected is set so that a range of a distance from the rib waveguide to the area to which the metal electrode is connected is such that when the distance is changed, an effective refractive index of the rib waveguide in a zeroth-order mode does not change.
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.
Abstract:
A one-dimensional photonic crystal has a spatial distribution in which the refractive index periodically varies in a first direction that light is caused to be propagated and in which the refractive index is uniform in a second direction perpendicular to the first direction. An antireflective coating structure for the one-dimensional photonic crystal includes a thin-film having a refractive index and a thickness determined by a predetermined calculation method. A two or three-dimensional photonic crystal comprises two or more media that have different refractive indexes and are arranged in a two or three-dimensional pattern. An antireflective coating structure for the two or three-dimensional photonic crystal includes a thin-film comprising one of the media included in the photonic crystal. In the structure, the thin-film is disposed on an end face of the photonic crystal so as to increase the incident efficiency of light entering the photonic crystal. Thereby, the reflection of the photonic crystal is securely prevented in a simple manner.
Abstract:
An optical waveguide type optical terminator forms an optical waveguide structure including at least an optical absorption core (103) which is formed on a clad layer (102) and includes a portion composed of silicon in which an impurity of 1019 cm−3 or more is doped, and is used by being optically connected in series with an optical waveguide including a core (105) composed of silicon. The optical absorption core (103) is sufficient provided that, at least, an impurity of around 1019 cm−3 is doped therein. For example, its impurity concentration is sufficient provided that it falls within a range of 1019-1020 cm−3. The existence of this impurity causes absorption of light in the optical absorption core (103).
Abstract:
Provided is a connecting channel that has manufacturing tolerance, can suppress light loses, improves reliability of the connecting channel, and connects an optical device and an optical waveguide. The connecting channel includes first silicon layer (3) that has rib-shaped part (3′) extending in a longitudinal direction of the connecting channel, and second silicon layer (6) that is stacked on first silicon layer (3) to partially overlap rib-shaped part 3′, and extends in the longitudinal direction. Second silicon layer (6) has tapered part (W) tapered toward one end in the longitudinal direction, and is located away from an upper portion of rib-shaped part (3′) at an end surface of one end in the longitudinal direction.
Abstract:
The present invention provides a small optical waveguide structure capable of converting the spot size of light, and capable of reducing the conversion loss when compared under the condition of the same waveguide length and performing an optical conversion with high efficiency. An optical waveguide structure (100) includes a base waveguide (110) including a taper section (111) whose width becomes continuously narrower from one side toward another side, and a narrow-width section (112) that is consecutively connected to a narrow-width side of the taper section (111) and extends toward the another side. In the optical waveguide structure (100), at least three-layered upper waveguides (121 to 123) each of which has a planar shape smaller than the taper section (111) and includes a planar-view-roughly-wedge-shaped section whose width becomes continuously narrower from the one side toward the another side at least on a tip side are stacked above the taper section (111) of the base waveguide (110) in such a manner that the planar shape becomes successively smaller from the base waveguide side (110).
Abstract:
In an electro-optic device, a stack structure including a first silicon layer of a first conductivity type and a second silicon layer of a second conductivity type has a rib waveguide shape so as to form an optical confinement area, and a slab portion of a rib waveguide includes an area to which a metal electrode is connected. The slab portion in the area to which the metal electrode is connected is thicker than a surrounding slab portion. The area to which the metal electrode is connected is set so that a range of a distance from the rib waveguide to the area to which the metal electrode is connected is such that when the distance is changed, an effective refractive index of the rib waveguide in a zeroth-order mode does not change.