INTEGRATED DOWNCONVERTER WITH POLARIZATION DIVERSITY FOR COHERENT OPTICAL RECEIVER WITH POLARIZATION MULTIPLEXING

Description

Optical Integrated Receivers (ORI) are a fundamental component for the new generation fiber optic communication systems, which are beginning to be commercialized and which are based on coherent modulations with polarization multiplexing.
Due to problems associated with manufacturing tolerances, the existing ORI configurations on the market (such as those of OCLARO and U2t) have not managed to monolithically integrate the Polarization Diversity Network (PDN) with the rest of the components. which forces the PDN to be placed outside the chip using 'bulk' technology (non-integrated), which increases the size and, above all, the cost of the receiver, since these 'bulk' components must be assembled manually.
In this invention a new type of PDN is proposed that allows the polarization separation function to be perfectly carried out and that does not present the problems of sensitivity to manufacturing tolerances of existing solutions to date. This invention will allow the entire ORI to be monolithically integrated into a single ‘chip’, using the same technology currently used to integrate only one part, which offers the possibility of achieving great cost savings. In addition, this solution would allow to directly replace the existing ORIs, without the need to complicate the rest of the communication system components.

Advantages

The most novel aspect of this proposal is that, for the first time, it is shown that with a suitable arrangement of the input waveguides of the optical circuit it is possible to perform the polarization separation function perfectly without the need to use 'polarization separators' . This is important, as it is well known that 'polarization splitters' are very difficult to realize in integrated optical technology due to the extreme sensitivity to manufacturing tolerances.
The advantage of this invention is that it will reduce the cost of manufacturing the new generation 100 Gb / s optical communications receivers that make use of polarization multiplexing, since it will allow all the subsystems of a receiver to be carried out on a single 'chip'. POLMUX coherent optical communications: the polarization diversity network, the phase diversity network and the photodiodes.

Uses and Applications

The main application of this invention is in the field of optical communications and, within them, you may have special interest in the equipment used in fiber optic communication trunk links that, in the near future, will use polarization division multiplexing. . Although this application is the most obvious, the invention could also be of interest in the field of sensors, since this invention would make it possible to have low-cost receivers for the simultaneous monitoring of the amplitude, the phase, and the state of polarization of the captured light. by the sensor.