Integrated silicon nitride based TE dual-band grating coupler

Summary form only given. Grating based fiber-chip couplers are an excellent scheme to couple between a sub-micron waveguide and an optical fiber. However, the operation bandwidth of the grating couplers is restricted to a particular wavelength band though high-coupler efficiency is achievable. An application such as Passive Optical Networks that use both O and C-band, it becomes essential to that grating couplers can be operated in two wavelength bands. We found very limited work on dual/multi-band grating coupling, which is an important part of a PON transceiver. However, dual-band grating with polarization splitting has been previously reported [2] in SOI platform. In this work, we propose and demonstrate a dual-band grating operating in O and C-band. The proposed dual-band grating coupler is implemented in Silicon Nitride (SiN) waveguide platform that is starting to emerge as an attractive alternative photonics circuit platform [3]. Unlike earlier demonstrations, both bands are directed to a single waveguide. To the best of our knowledge, this is the first ever demonstration of a unidirectional single polarization dual band grating couple.