Abstract:
PROBLEM TO BE SOLVED: To provide an optical modulator which can fully modulate optical carrier waves by an extremely small modulation voltage. SOLUTION: The optical modulator is provided with a beam splitter, an interferometer which has first and second parallel optical branches and a beam combiner, intrinsic semiconductor crystal plane layers which respectively have (p) type and (n) type plane semiconductor layers on their opposite surfaces and are arranged on the planes parallel to the propagation direction of the laser beams within the respective optical branches, a plurality of quantum-dot plane array layers which are arranged on the intrinsic semiconductor layers, a DC reverse bias voltage source which is connected to both ends of the (p) type and the (n) type layers, a pair of modulation source terminals which are connected to the both ends of the DC reverse bias voltage source and act to modulate the reverse bias voltage of the both ends of the (p) type and (n) type layers by a modulation signal. The modulator is provided with first and second optical phase shifters which are respectively arranged within the first and second parallel optical branches. COPYRIGHT: (C)2004,JPO
Abstract:
The invention relates to an electro-optic Mach-Zehnder modulator arrangement, comprising - a first optical waveguide (11) forming a first arm of the Mach-Zehnder modulator (1, 100); - a second optical waveguide (12) forming a second arm of the Mach-Zehnder modulator (1, 100); - an electrode arrangement (2) comprising at least one first waveguide electrode (21, 210) output port (441, 4410) coupled to the first waveguide electrodes (21, 210)and at least one second waveguide electrode (22, 220) arranged on top of a capacitive segment (111, 1110, 121, 1210) of the first and the second optical waveguide (11, 12), respectively, such that a voltage can be applied across the capacitive segments (111, 1110, 121, 1210) of the first and second optical waveguide (11, 12); - at least one driver unit (41, 410) for supplying a voltage (V) to the electrode arrangement (2), the driver unit (41, 410) comprising at least a first output port (441, 4410) coupled to the first waveguide electrodes (21, 210) and a second output port (442, 4420) coupled to the second waveguide electrodes (22, 220), wherein - the driver unit (41) is configured to supply a first varying signal (S+) to the first waveguide electrodes (21) via the first output port (441) and to supply a second varying signal (S-) to the second waveguide electrodes (22) via the second output port (442); and - a non-grounded conductive region (3, 30) via which the capacitive segment (111, 1110) of the first optical waveguide (11) is connected to the capacitive segment (121, 1210) of the second optical waveguide (12) such that the first and second waveguide electrodes (21, 210, 22, 220) are capacitively coupled to one another. The invention also relates to a method for operating a Mach-Zehnder modulator arrangement.
Abstract:
A silicon-based optical modulator structure (20) includes one or more separate localized heating elements (22/24) for changing the refractive index of an associated portion of the structure and thereby providing corrective adjustments to address unwanted variations i device performance Heating is provided by thermo-optic devices such as, for example, silicon- based resistors, silicide resistors, forward-biased PN junctions, and the like, where any of these structures may easily be incorporated with a silicon-based optical modulator The application of a DC voltage to any of these structures will generate heat, which then transfers into the waveguiding are The increase in local temperature of the waveguiding area will, in turn, increase the refractive index of the waveguiding in the area Control of the applied DC voltage results in controlling the refractive index
Abstract:
An optical waveguide that guides an incident light is formed on an a substrate having an electro−optical effect. A first buffer layer is formed so as to cover the top surface of the substrate. A conductive film is formed above the first buffer layer. A center electrode and a groung electrode are formed to apply voltage to the optical waveguide so as to induce an electric field therein. A second buffer layer is formed between the conductive film and at least one of the center electrode and the ground electrode. The conductive film is so formed as to exist at least a part of and below the ground electrode. Light guided along the optical waveguide is modulated by having the phase thereof changed by voltage applied to the optical waveguide. Accordingly, an optical modulation device is provided that has an excellent electric characteristics by effectively restricting heat drift.
Abstract:
An electro-optic modulator having a continuously adjustable chirp is provided. Optical signals input into the electro-optic modulator are divided into portions which are phase modulated in opposite senses, one portion imparted with a positive chirp and the other with a negative chirp. Variable couplers are used to adjust (by way of adjusting their coupling ratios) the amount of power allocated between the optical signals contributing to the positive chirp and the power of signals contributing to the negative chirp so that when the optical signals are combined an optical signal with an adjustable chirp is produced.
Abstract:
A method for controlling an optoelectronic component that includes two waveguides (3 and 4). The refractive index of the first waveguide (3) is changed periodically with a first control signal (1), the amplitude of which is changed between a first amplitude level (I) and higher second amplitude level (II). The refractive index of the second waveguide (4) is changed periodically with a second control signal (2), the amplitude of which is changed between the aforementioned first amplitude level (I) and a lower third amplitude level (III). When the control signals are on their common first amplitude level (I), the refractive indices of the waveguides are equal and the phase difference between them is zero. When the first control signal is on the second amplitude level (II) and the second control signal on the third amplitude level (III), the refractive indices of the waveguides are unequal so that their mutual phase difference has a predetermined target value. For accelerating a phase-difference change both control signals are adjusted during both the rise and the fall time periods simultaneously so that their combined effect leads to a very fast phase difference change, which settles already before the refractive indices of the waveguides are settled.
Abstract:
An optical waveguide for guided an incident light is formed on a substrate having an electro-optic effect. A first buffer layer is formed to cover an upper surface of the substrate. A conductive film is formed above the first buffer layer. A center electrode and a ground electrode are formed for applying a voltage in order to induce an electric field in the optical waveguide. A second buffer layer is formed between the conductive film and at least one of the center electrode and the ground electrode. The conductive film is formed to be present on at least a part below the ground electrode. A light guided through the optical waveguide is modulated by changing a phase by a voltage applied to the optical waveguide. Thereby, a thermal drift can be effectively restricted so that an optical modulation device having excellent electric characteristics can be realized.