The work of Ph.D. student Shen Jian on "Ultralow-power piezo-optomechanically tuning on CMOS-compatible integrated silicon-hafnium-oxide platform" has recently been accepted and published by Laser & Photonics Reviews as a cover paper. This work was partially supported by the National Key R&D Program of China (2019YFB2203601) and the National Natural Science Foundation of China (61975115/61835008). The authors introduced doped hafnium oxide film as the guiding layer and piezoelectric layer, and developed a CMOS-compatible integrated silicon-hafnium-oxide platform for photonics. They designed and experimentally demonstrated a piezoelectrically tunable micro-ring resonator based on a silicon-hafnium-oxide hybrid waveguide, achieving linear bidirectional wavelength tuning with a tuning power three orders of magnitude lower than traditional silicon thermal-optical tuning schemes. This expands the device library of silicon photonics integration technology and opens up new avenues for the application of CMOS-compatible piezoelectric drivers in fully integrated silicon photonics chips.
Abstract: Power consumption of photonic integrated circuits becomes a critical consideration. We propose a new platform for ultra-low-power tuning in silicon photonics via piezo-optomechanical coupling using hafnium-oxide actuators. As an example of the potential of the platform, we demonstrate a tunable silicon-hafnium-oxide hybrid microring, where hafnium-oxide film acts as an active optical and piezoelectric layer. The hybrid microring is capable of linear bidirectional tuning with a wavelength tuning efficiency of 8.4 pm/V and a power efficiency of 0.12 nW/pm. The estimated power consumption for tuning a free spectral range (FSR) in hybrid microring is 3.07 μW/FSR. Our hybrid silicon-hafnium-oxide technology with complementary metal-oxide-semiconductor (CMOS) compatibility advances the field of ultra-low-power integrated photonic devices and can find applications in optical communications, computing, and spaces under cryogenic temperatures.