Polarization independent and temperature tolerant AWG based on a silicon nitride platform

Abstract

Polarization tolerant optical receiver is a key building block for the development of wavelength division multiplexing (WDM) based high-speed optical data links. However, the design of polarization independent demultiplexer (DEMUX) is not trivial. In this work, we report on the realization of a polarization tolerant arrayed waveguide grating (AWG) on a 300-mm silicon nitride (SiN) photonics platform. By introducing a series of individual polarization rotators in the middle of the waveguide array, the polarization dependence of the AWG has been substantially reduced. Insertion losses below 2.2dB and a crosstalk level better than -29dB has been obtained for TE and TM polarizations on a four channel coarse AWG. The AWG temperature sensitivity has also been evaluated. Thanks to the low thermo-optical coefficient of SiN, a thermal shift below 12pm/°C has been demonstrated.

Polarization-independent wavelength demultiplexer based on a single etched diffraction grating device

“…The polarization dispersion in the FPR slab waveguide can be regulated by changing its material and thickness. In this study, Si 3 N 4 was selected because of its low propagation loss, low thermo-optical effect, and complementary metal-oxide-semiconductor processing compatibility 28 , 36 . The effective refractive indices of the TE and TM fundamental modes in the FPR slab waveguides of different Si 3 N 4 layer thicknesses were simulated, as shown in Fig.…”

“…Finally, they are converted back to different TE/TM polarizations for combination and output. Recently, researchers have developed more simplified polarization-independent demultiplexers by cascading a single demultiplexer with polarization-handling devices such as a polarization beam splitter 25 , 26 or a series of polarization rotators 27 , 28 . In these devices, the polarization dispersions are compensated with the angular dispersion via polarization beam splitters or polarization rotation via polarization rotators.…”

Library of single-etch silicon nitride grating couplers for low-loss and fabrication-robust fiber-chip interconnection

“…To date, a rich library of Si 3 N 4 photonic devices has been demonstrated. This includes low-loss waveguides 9 , filters 10 , splitters 11 , multiplexers 12 , ring resonators 13 , and grating and edge couplers 14 – 16 , among others. Compared to SOI waveguides, the index contrast between the Si 3 N 4 light-guiding layer and the claddings is more moderate, typically ~ 0.5 (cladded with silica) and ~ 1.0 (cladded with air), hence it is challenging to obtain a low-loss interconnection between off-chip environment and SiN dies.…”

Wavelength beam combining of 850 nm and 2000 nm lasers based on an adiabatic optical coupler

“…Therefore, on-chip beam combing technology is of great interest for the development of broadband optical communication, multi-species trace gas sensing and bio-sensing. Photonic integrated devices such as multimode interferometers (MMIs) and arrayed waveguide gratings (AWGs) can be used as the wavelength beam combiners [3,4]. The MMI-based wavelength beam combiners are usually quite compact, but the bandwidth is only a few hundred meters [5].…”