Ultra-Compact Efficient Thermally Actuated Mach-Zehnder Modulator Based on VO2

• Published in: IEEE access 2022, Vol.10, p.85952-85959
• Main Authors: Mohammadi-Pouyan, Sohrab, Afrouzmehr, Moein, Abbott, Derek
• Format: Article
• Language: English
• Subjects: C band; Mach-Zehnder interferometer; Mach-Zehnder interferometers; Modulation; Optical device fabrication; Optical devices; Optical imaging; Optical modulation; Optical refraction; Optical variables control; phase change material; thermo-optical modulator; vanadium dioxide
• ISSN: 2169-3536
• DOI: 10.1109/ACCESS.2022.3197163

Vanadium dioxide (VO 2 ) has emerged as a prominent optical phase change material (O-PCM) for creating high performance devices based on hybrid silicon platforms. However, realizing an efficient and compact optical modulator required for Mach-Zehnder interferometer (MZI) structures, still remains a major challenge in active Si-platforms enabled by VO 2 . This is mainly due to the simultaneous variation of both real and imaginary parts of the refractive index during the phase transition process, which is a significant issue. A modified MZI structure is proposed in this paper while the refractive index variation issue is overcome by operating in the wavelength range between 1.5 to 1.6~\mu \text{m} including the optical C-band. An indium tin oxide (ITO) layer is considered as the microheater for the thermal excitation. An optimized triggering signal with an amplitude of 12.5 V along with an arm length of 2.35~\mu \text{m} of the MZI device ( V_{\pi }L_{\pi }= 30 \,\,\text {V}\cdot \mu \text{m} ) established a \pi -shift at the output of the device. The proposed device has ER >35 dB at the entire optical C-band and consumes \sim 26 pJ for modulating a single bit with a delay of 3.5 ns.