Applications of recirculating optical configurations on filters and lasers

Abstract

In this paper, different optical configurations based on ring resonators and a reflective section in the feedback path, are proposed in order to show the feasibility of their applications in different fields. Additionally, the use of optical amplification in some of the configurations offers the possibility of improving the device insensibility to fabrication tolerances and gives flexibility to the designs. In the compounds configurations that use reflective elements in the ring resonators, such as Sagnac configurations and Bragg Gratings, tuning is achieved by changing the coupling ratio of a coupler apart from conventional tuning by changing the equivalent loop length, using temperature or injection current. Applications as tunable filters in DWDM networks and lasers will be discussed. The reported structures can be integrated in InP or silicon technology, because photonics circuits with equivalent components have already been developed. Some of them are a monolithically integrated Sagnac interferometer for an all-optical controlled-NOT gate. Integrated optic devices have higher free spectral ranges, thus complying with applied standards on DWDM networking. Theoretical analysis is presented to identify and emphasize the design parameters of each configuration as regards its application of interest. Measurements on fibre optic prototypes for showing the principle of operation and validating the theoretical models are reported in [24].