Ridge waveguide serial interferometers
In a ridge waveguide serial interferometer mode conversion is induced by a first mode conversion section, a phase difference between modes is introduced by propagation over a length of waveguide and optical interference is produced following further mode conversion induced in a second mode conversion section. The first mode conversion section has a first radius of curvature, which is equal to a second radius of curvature of the second mode conversion section. The ridge waveguide interferometer advantageously provides an equal phase dependency as a function of temperature.
1. A ridge waveguide optical wavelength monitoring device that is part of a wavelength locker, the device comprising a ridge waveguide having a first mode conversion section, a second mode conversion section, and an intermediate section coupled between the first and second mode conversion sections, the first and second mode conversion sections being adapted to induce mode conversion between optical modes of light transmitted within the ridge waveguide,
wherein the first mode conversion section has a first radius of curvature, the second mode conversion section has a second radius of curvature and the first and second radii of curvature are substantially equal, wherein an input section is coupled to the first mode conversion section at an end distal from the intermediate section and is adapted to substantially transmit a fundamental mode, and wherein an output section is coupled to the second mode conversion section at an end distal from the intermediate section and is adapted to substantially transmit the fundamental mode and a higher order mode.
2. A device according to claim 1 , further comprising a photodetection section coupled to an output end of the second mode conversion section.
3. A device according to claim 2 , wherein the photodetection section comprises a first photodetector, a second photodetector and a mode filter optically coupled between the first and second photodetectors.
4. A device according to claim 3 , wherein the mode filter is a 1×1 multimode interference coupler.
5. A device according to claim 1 , wherein the intermediate section is provided with a tuning electrode.
6. A device according to claim 1 , further comprising a Mach-Zehnder interferometer section.
7. A device according to claim 1 , further comprising an electrical control system.
8. An environmental sensor comprising a device according to claim 1 .
9. An optoelectronic module comprising a device according to claim 1 .
10. A device according to claim 1 , which device is a serial interferometer.