[18a-WL2_401-1~11] 3.13 Silicon photonics, Photonics-electronics convergence, Optical control

11:00 AM - 11:15 AM JST(2:00 AM - 2:15 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation AwardEnglish Presentation

[18a-WL2_401-8] Pockels Effect in Hf_0.5Zr_0.5O₂ Integrated Silicon Nitride Waveguides

〇Wei Dai¹, Zhenhong Liu¹, Hiroyuki Matsukawa¹, Kasidit Toprasertpong¹, Mitsuru Takenaka¹ (1.Tokyo Univ.)

Keywords:

Ferroelectricity,Optical Modulator,Pockels Effect

Ferroelectric materials exhibiting the Pockels effect are promising for realizing low-power optical phase shifters in photonic integrated circuits. Hafnium oxide–based ferroelectrics are particularly attractive due to their CMOS compatibility, yet their electro-optic properties in integrated photonic devices remain underexplored. In this work, we investigate the electro-optic response of ferroelectric Hf_0.5Zr_0.5O₂ (HZO) thin films integrated with silicon nitride (SiN) waveguides. Phase modulation is characterized using a Mach–Zehnder interferometer after electric-field poling of a 60-nm-thick HZO layer deposited by atomic layer deposition. The voltage-dependent refractive index modulation exhibits a quadratic behavior with a polarity-dependent offset, indicating the superposition of quadratic Kerr and linear electro-optic effects. The sign reversal of the offset with inverted poling polarity provides clear evidence of a Pockels effect originating from ferroelectric polarization in HZO. By fitting the modulation response, an effective electro-optic coefficient of 1.25 pm/V, primarily corresponding to the r₃₃ component, is extracted. These results demonstrate the potential of ferroelectric HZO for CMOS-compatible, low-power electro-optic phase shifters.