Design Of Silicon-Based Optical Switching Chip And Its Performance Evaluation

Optical switching node is one of the core elements of all-optical switching network, and the realization of high-speed optical switching integration chips helps to build up optical switching node. Silicon-based optical switching chips have been a hot research topic in the field of on-chip optical communications because of their manufacturing compatibility with conventional CMOS technology as well as easy realization of monolithic integration. In this paper, we perform the experimental test of the 4×4 optical switching chip, and put forward a theoretical model of crosstalk for optical switching integration chips, which is used to optimize the design of switch units. The main content is listed as follows:1. A theoretical model was put forward to simplify the crosstalk analysis of integrated optical switching chips, by comprehensively considering the insertion loss and crosstalk dependency on optical switch routing. The chip’s crosstalk can be expressed as the weighted summation of switch crosstalk, in which the weight coefficients are the relative routing loss coefficients.2. The chip layout design and fabrication(by foundry) was accomplished by optimizing these basic units of optical switching chip by ModeSolution simulation. The measured results show that,(1) for the 2×2 MZI switching unit, the insertion loss is 1.92 dB, the crosstalk is below-16 dB and the 3-d B bandwidth is larger than 40nm;(2) for the 2×2 SRMZI switching unit, the insertion loss is 2.13 dB, the crosstalk is-23.72 dB and the 3-dB bandwidth is 43.5GHz. And then, we evaluate the resulting 16×16 optical switching chips using our crosstalk model, which meet the design requirements of the project.3. The fiber-to-fiber switching and transmission experiments of 4×4 MZI optical switching chip system were carried out by means of four 40 Gbps DQPSK-modulated signals. Under normal working conditions, the switching time is less than 20 ns. The experiments show that the optical switching chip under NIN thermal compensation has the max insertion loss of about 23.53 dB, and the max crosstalk of-28.66 dB. In the full load, all 24 error-free switching states can be obtained by appropriately selecting the switch routs. The testing methods used in the paper are also useful for the 16×16 integrated optical switching chips.