An Optical 1×4 Power Splitter Based on Silicon–Nitride MMI Using Strip Waveguide Structures

Abstract

This paper presents a new design for a 1 × 4 optical power splitter using multimode interference (MMI) coupler in silicon nitride (Si3N4) strip waveguide structures. The main functionality of the proposed design is to use Si3N4 for dealing with the back reflection (BR) effect that usually happens in silicon (Si) MMI devices due to the self-imaging effect and the higher index contrast between Si and silicon dioxide (SiO2). The optimal device parameters were determined through numerical optimizations using the beam propagation method (BPM) and finite difference time domain (FDTD). Results demonstrate that the power splitter with a length of 34.6 μm can reach equal distribution power in each output port up to 24.3% of the total power across the O-band spectrum with 0.13 dB insertion loss and good tolerance MMI coupler parameters with a shift of ±250 nm. Additionally, the back reflection range over the O-band was found to be 40.25–42.44 dB. This demonstrates the effectiveness of the incorporation using Si3N4 MMI and adiabatic input and output tapers in mitigating unwanted BR to ensure that a good signal is received from the laser. This design showcases the significant potential for data-center networks, offering a promising solution for efficient signal distribution and facilitating high-performance and reliable optical signal routing within the O-band range. By leveraging the advantages of Si3N4 and the MMI coupler, this design opens possibilities for advanced optical network architectures and enables efficient transmission of optical signals in the O-band range.

O-Band Grating Couplers Using Silicon Nitride Structures

“…The grating period between the grooved teeth, denoted as Λ, has been set to 0.84 µm, where the SiO2 width of each grooved tooth is 0.34 µm, represented by W, and In our model, we selected the GC based on a uniformly grooved teeth configuration for its ease of fabrication and compact footprint, which leads to low-cost GC devices. It is important to emphasize that while complex configurations, such as using a reflector [35,36], a GC with non-uniform grooved teeth [37][38][39][40][41][42], or edge couplers [38], can improve coupling efficiency, they also introduce fabrication difficulties and increased costs. For example, the reflectors used in GCs are sensitive to fabrication variations, such as dimensional errors or imperfections in the grating structure.…”

Data Center Four-Channel Multimode Interference Multiplexer Using Silicon Nitride Technology

“…The multiplexer’s design is based on the principle of multimode interference (MMI), which allows for the uniform distribution of light from multiple input ports toward the output port via the self-imaging effect [ 11 , 12 , 13 ]. The design also takes advantage of silicon nitride (Si 3 N 4 ), a material with low propagation loss, high thermal stability [ 14 ], and compatibility with standard complementary metal-oxide-semiconductor (CMOS) manufacturing processes [ 15 , 16 ], making it an ideal material for integrated photonic applications.…”

Designing an Optical Router Based on a Multimode-Interference Silicon-On-Insulator Coupler with Tunable Power Transmittance

“…Optical routers and multiplexers show high potential for transferring data between optical nodes with speeds matching the high-speed data transmission through optical fibers. Optical routers and splitters [3] based on integrated optical devices are usually based on photonic components such as multimode interferometers (MMIs) [4][5][6], Mach Zender interferometers [7,8], directional couplers [9,10], and ring resonators [11,12].…”