Athermal and tunable echelle grating wavelength demultiplexers using a Mach-Zehnder interferometer launch structure

TL;DR

This paper demonstrates silicon photonic echelle grating demultiplexers with integrated Mach-Zehnder interferometers that enable athermal operation, enhanced or suppressed wavelength tuning, and active temperature compensation with low power.

Contribution

It introduces configurable MZI launch structures for silicon photonic demultiplexers, enabling tunable and athermal wavelength operation with low power consumption.

Findings

Athermal configuration reduces spectral shift to <10 pm/°C.

Super-thermal operation achieves 170 pm/°C tuning rate.

Active temperature compensation up to 20°C with <20 mA current.

Abstract

We present a comparative experimental study of three silicon photonic echelle grating demultiplexers that are integrated with a Mach-Zehnder interferometer (MZI) launch structure. By appropriate choice of the MZI configuration, the temperature induced shift of the demultiplexer channel wavelengths can be suppressed (athermal) or enhanced (super-thermal), or be controlled by an on-chip micro-heater. The latter two configurations allow the channel wavelengths to be actively tuned using lower power than possible by temperature tuning a conventional echelle demultiplexer. In the athermal configuration, the measured channel spectral shift is reduced to less than 10 pm/C, compared to the 83 pm/C shift for an unmodified echelle device. In super-thermal operation an enhanced channel temperature tuning rate of 170 pm/C is achieved. Finally, by modulating the MZI phase with an on-chip heater, the demultiplexer channels can be actively tuned to correct for ambient temperature fluctuations up to 20 C, using a drive current of less than 20 mA.