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US 6,721,085 B2Granted
Optical modulator and design method therefor
AssigneeFujitsu Limited
InventorsMasaki Sugiyama, Tadao Nakazawa
Life of this patent
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Abstract
A high-speed, high-performance optical modulator operating with a reduced drive voltage without sacrificing modulation bandwidth. The modulator has an optical waveguide fabricated on a crystal substrate. A signal electrode is on a ridge on the substrate. Ground electrodes are formed on both sides of the signal electrode. A gap between the signal and ground electrodes is at least 44 μm, and an interaction length of the signal electrode is at least 41 mm. The modulator can operate at 40 Gbps or higher.
Claims83
An apparatus comprising:
- an optical modulator comprising
- a ridge;
- a signal electrode on the ridge, the signal electrode having an interaction length which is at least 41 mm;
- and
- a ground electrode, wherein a gap width between the ground electrode and the signal electrode is at least 44 μm.
2 more elements
An optical modulator for optically modulating a light, comprising
- a substrate;
- an optical waveguide through which the light travels;
- a ridge changing an elevation of the optical waveguide with respect to the substrate;
- a ground electrode;
- a signal electrode on the ridge, a gap width between the ground electrode and the signal electrode being at least 44 μm, the signal electrode having an interaction length with respect to the optical waveguide of at least 41 mm, a drive signal supplied to the signal electrode causing an electric field to be produced along the optical waveguide as the light travels through the optical waveguide, to optically modulate the light.
2 more elements
An optical modulator for optically modulating a light, comprising
- a substrate;
- an optical waveguide through which the light travels;
- a ridge changing an elevation of the optical waveguide with respect to the substrate;
- first and second ground electrodes;
- a signal electrode on the ridge and positioned between the first and second ground electrodes, a gap width between the first ground electrode and the signal electrode, and between the second ground electrode and the signal electrode, being at least 44 μm, the signal electrode having an interaction length with respect to the optical waveguide of at least 41 mm, a drive signal supplied to the signal electrode causing an electric field to be produced along the optical waveguide as the light travels through the optical waveguide, to optically modulate the light.
2 more elements
An optical modulator for optically modulating a light, comprising
- a z-cut LiNbO3 substrate;
- an optical waveguide through which the light travels;
- a ridge changing an elevation of the optical waveguide with respect to the substrate;
- first and second ground electrodes;
- a signal electrode on the ridge and positioned between the first and second ground electrodes, a gap width between the first ground electrode and the signal electrode, and between the second ground electrode and the signal electrode, being at least 44 μm, the signal electrode having an interaction length with respect to the optical waveguide of at least 41 mm;
- and
- a buffer layer between the signal electrode and the ridge, wherein a drive signal supplied to the signal electrode causes an electric field to be produced along the optical waveguide as the light travels through the optical waveguide, to optically modulate the light.
4 more elements
An optical modulator comprising
- a crystal substrate that exhibits an electro-optic effect;
- an optical waveguide through which a light travels;
- a ridge changing an elevation of the optical waveguide with respect to the substrate;
- first and second ground electrodes;
- a signal electrode on the ridge and between the first and second ground electrodes, a gap width between the signal electrode and the first ground electrode, and between the signal electrode and the second ground electrode, being at least 44 μm, the signal electrode having an interaction length with respect to the optical waveguide of at least 41 mm, wherein
- the light traveling through the optical waveguide is phase-matched with a microwave signal traveling through the signal electrode, and
- characteristic impedance of the signal electrode is set within a range where microwave reflection is limited below a predetermined level, to thereby optically modulate the light.
4 more elements
An optical modulator comprising
- a z-cut LiNbO3 substrate;
- an optical waveguide through which a light travels;
- a ridge changing an elevation of the optical waveguide with respect to the substrate;
- first and second ground electrodes;
- a signal electrode on the ridge and between the first and second ground electrodes, a gap width between the signal electrode and the first ground electrode, and between the signal electrode and the second ground electrode, being at least 44 μm, the signal electrode having an interaction length with respect to the optical waveguide of at least 41 mm, and
- a buffer layer between the signal electrode and the ridge, wherein
- the light traveling through the optical waveguide is phase-matched with a microwave signal traveling through the signal electrode, and
- characteristic impedance of the signal electrode is set within a range where microwave reflection is limited below a predetermined level, to thereby optically modulate the light.
5 more elements
Dependencies are inferred from the claim text.