Abstract
We report the design and fabrication of a compact angled multimode interferometer (AMMI) on a 600nm thick N-rich silicon nitride platform (n=1.92) optimized to match the International Telecommunication Union coarse wavelength division (de)multiplexing standard in the O telecommunication band. The demonstrated device exhibited a good spectral response with Δλ=20 nm, BW3 dB∼11 nm, IL<1.5 dB, and XT∼20 dB. Additionally, it showed a high tolerance to dimensional errors <120 pm/nm and low sensitivity to temperature variations <20 pm/°C, respectively. This device had a footprint of 0.02 mm×1.7 mm with the advantage of a simple design and a back-end-of-line compatible fabrication process that enables multilayer integration schemes due to its processing temperature <400°C.
Highlights
Wavelength divisionmultiplexing devices (WDM) capable of splitting/combining the light into/from multiple wavelengths are components required for a wide variety of photonic applications, to increase the capacity of high-speed telecommunication photonic integrated circuits
Hu et al proposed angled-multimode interferometer (AMMI)multiplexers based on multimode dispersive waveguides capable of providing low insertion losses (IL) with a high tolerance to fabrication errors [4]
The mean XT between adjacent channels is ∼21dB with a maximum XT nonuniformity of 11dB. This strong XT non-uniformity is produced by the difference in the free spectral range (FSR) of the channels
Summary
Wavelength division (de)multiplexing devices (WDM) capable of splitting/combining the light into/from multiple wavelengths are components required for a wide variety of photonic applications, to increase the capacity of high-speed telecommunication photonic integrated circuits. WDM devices demonstrated in literature include arrayed waveguide gratings, planar concave gratings and micro-ring resonators [1,2,3] All these devices have been realised in a variety of platforms, including silica and silicon-on-insulator (SOI), which pose different challenges that must be overcome to achieve competitive performances. Devices on the SOI platform tend to be compact but they exhibit higher losses and a higher sensitivity to both dimensional and temperature variations. To address this situation, Hu et al proposed angled-multimode interferometer (AMMI) (de)multiplexers based on multimode dispersive waveguides capable of providing low IL with a high tolerance to fabrication errors [4]. SOI AMMIs are still prone to a low tolerance to temperature variations due to the large thermo-optic coefficient of Si ∼1.8x10-4/°C
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