Toward athermal silicon-on-insulator (de)multiplexers in the O-band

Abstract

We report on the design, fabrication, and characterization of a 1×4 silicon-on-insulator (SOI) demultiplexer exhibiting a significant reduction of its thermo-optical sensitivity in the O-band. The optical filtering is achieved by cascading several Mach-Zehnder interferometers (MZIs) fabricated on a 300-nm-thick SOI platform. Owing to an asymmetric design of the confinement for each MZIs, we found an athermal criterium that satisfies the spectral requirements. The thermal sensitivity of the structure is analyzed by a semi-analytical model in order to create an athermal multiplexer. Fiber-to-fiber thermo-optical testing reveals a thermal sensitivity of around 17 pm/°C reduced by 75% compared to the standard devices with promising performances for both the crosstalk (15 dB), the insertion losses (4 dB), and absolute lambda registration (<0.25 nm).

Athermal and flat-topped silicon Mach-Zehnder filters

“…For a silicon WDM filter, another main requirement is the athermal transmission spectrum since the large positive thermo-optic coefficient of silicon material (TOC ∼1.86 × 10 −4 K −1 ) will cause considerable temperature dependent wavelength shift (~80 pm/K). Aiming at athermal filters, several methods have been reported, such as cladding with negative TOC materials [15][16][17], coupling with multiple structures [18,19], and combination of multiple types of waveguide [20][21][22][23][24][25]. Constructing the arms of a MZ filter with the combination of multiple types of waveguide is the most promising athermal scheme, as summarized in [2], due to the merits of CMOScompatible fabrication process and zero extra energy consumption.…”

Advances toward temperature-independent and fabrication-insensitive (de)multiplexer in the O-band

“…For each MZI, additional waveguide sections using two different widths of 400nm and 200nm (in S-shape for more compactness) are placed in order to change the thermo-optical sensitivity of each arm and consequently to lock the phase difference for any temperature on a reasonable bandwidth (the length difference creates the interference pattern and the width difference averages the thermal drifts). Finally, one can link the thermo-optical and opto-geometrical constraints together and propose an athermal criterium that also respects the filtering pattern given by the 100GBASE-LR4 norm here (channel positions, spacing,...) [12]. This athermal-MUX (AMUX) is then fabricated using the same platform as described in Section I, and next characterized with fiber-to-fiber thermo-optical measurements.…”

Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material

“…In addition to simple devices, e.g. ring resonators and Mach-Zehnder interferometers(MZI), many have demonstrated (de)multiplexers and switches with heaters [12]. Nevertheless, the extra power consumption and the required electronic interconnects for feedback systems eventually limit integration density, scalability and their size.…”

“…In Si Photonic devices this can be done either by special MZI or microring assisted MZI designs [12][13][14][15][16], or through utilizing a hybrid material approach by incorporating negative thermo-optic coefficient (TOC) materials as cladding layers. In the latter, the first athermal silica photonic devices were demonstrated using polymers in the O and C band [17][18][19].…”