A Low-Loss and Broadband MMI-Based Multi/Demultiplexer in Si₃N₄/SiO₂Technology

Abstract

A low-loss and broadband multimode interference (MMI)-based wavelength multi/demultiplexer in Si 3 N 4 /SiO 2 technology for erbium-doped lasing and amplifying applications is presented. The structural parameters of a 2 × 1 Si 3 N 4 MMI multi/demultiplexer are optimized to minimize losses. The design and analysis of the MMI multi/demultiplexer are carried out using a hybrid approach, which combines a modified effective index method, the 2D film mode matching method, and the 2D beam propagation method, with lower impact in the computing requirements and simulation time than 3D methods. Simulated total losses of 0.19 and 0.23 dB at 980 and 1550 nm, respectively were obtained for the optimized MMI multi/demultiplexer. The measurements of our fabricated couplers, with 110 nm thick Si 3 N 4 layer, show good agreement with our design. As multiplexers, the average losses of the MMI were measured to be 0.4 ± 0.3 dB for both 976 and 1550 nm wavelengths, and less than 1 dB across the whole C-band. As demultiplexers, the measured average extinction ratio of the fabricated MMI was found to be 21.4 ± 1.2 and 26.3 ± 0.8 dB for pump and signal wavelengths, respectively. Index Terms-Beam propagation and laser couplers, integrated optoelectronics, multi/demultiplexer, multimode interference (MMI), silicon nitride (Si 3 N 4 ).

High-gain waveguide amplifiers in Si3N4 technology via double-layer monolithic integration

“…The fabricated waveguides have a width of W P 1.4 0.08 μm and a measured propagation loss of 0.14 dB/cm at the wavelength of 1532 nm, measured using reference add-drop ring resonators. Multi/ demultiplexers for combining/splitting the pump and signal modes were integrated on the passive Si 3 N 4 waveguides [40].…”

“…The characterization used the same experimental setup as the work of Ref. [40]. By launching the signal light through the signal (S) port and pump (P) port, the MMI losses were measured to be 1.38 0.1 dB and 9.03 0.04 dB at the wavelength of 1532 nm, respectively.…”

“…On the left side, i.e., the input of signal light, the pump and signal are launched through different channels of a fiber array (127 μm pitch). They are multiplexed by the on-chip 2 × 1 MMI [40]. At the right side, after the 3 dB coupler, the pump passes first through the polarizationmaintaining wavelength-division multiplexer (980/1550 WDM, WP9850F), and then is launched into the pump port of the on-chip 1 × 2 MMI demultiplexer.…”

CORNERSTONE’s Silicon Photonics Rapid Prototyping Platforms: Current Status and Future Outlook

“…The different properties discussed above have made Si 3 N 4 an ideal candidate for the realization of a various linear and non-linear PICs spanning from visible to mid-infrared wavelengths. Si 3 N 4 has been widely used to demonstrate passive linear devices for datacom and visible wavelengths [89,90], including low loss waveguides [90,91], multimode splitters [83,92] and Mach-Zehnder interferometers [93]. Many research groups have worked on (de)multiplexers such as array waveguide gratings [94], angled-multimode interferometers [95,96] and echelle gratings [94,97].…”

Inverse Design and Demonstration of a Compact on-Chip Narrowband Three-Channel Wavelength Demultiplexer

“…Frandsen et al experimentally showed a drop-filter with 11 nm full-width-half-maximum (FWHM) [12], but the device only filters out one wavelength over a larger footprint than we demonstrate here. Recent experimental demonstrations of multimode interference (MMI) devices have also achieved demultiplexing capabilities in ultracompact footprints but again with large channel spacings over two channels [13,14]. Since the number of wavelengths available in a WDM system is inversely proportional to the channel spacing, WDM systems that utilize multiple wavelengths require demultiplexers with more channels and much smaller channel spacing.…”