Potential for large optical gain improvement of erbium-doped slot waveguide amplifiers in silicon photonics

Abstract

The potential for on-chip optical amplification at λs=1530 nm in silicon photonics using erbium-doped rich polymers integrated in silicon-slot waveguides is investigated by using a four-level spectroscopic model and a pumping wavelength of 1.48 μm. It is shown that the key parameter driving the whole amplification efficiency is the slot waveguide linear loss level, while optimization of the hollow core waveguide cross section leads to a slot width around 130 nm. Our investigations show that an on-chip optical gain of about 10 dB can be obtained with 7 dB/cm loss slot waveguides. Such a propagation loss is directly sustained by experimental results obtained for photonic structures fabricated using silicon technology. Due to the likelihood of improved technological processes in the near future, the slot waveguide loss level was swept in the 3–10 dB/cm range, showing that on-chip optical gain up to 30 dB can be seriously envisaged for slot waveguides with optimized optical losses around 3 dB/cm.