Phase-polarization ensemble modulation effect of a BaTiO₃ crystal film waveguide on Mach–Zehnder interferometer electrooptic intensity modulators

Abstract

In this work, based on the nonlinear electrooptic (EO) modulation model, the relationship between the polarization states and the birefringence modulation caused optical phase of c-axis barium titanate ( B a T i O 3 ) crystal film is investigated first. Then, under an ensemble effect of phase-polarization modulation (PPM), the photon polarization behavior of a lightwave in a B a T i O 3 film waveguide and its dynamic conversion process is clearly presented. Further, the optical output and optical phase changes of a Mach–Zehnder interferometric (MZI) type EO intensity modulator based on a dynamic nonlinear optical birefringence modulation are theoretically modeled. As a result, the systematic simulations show that, for one-wave ( 2 π ) optical phase modulation (OPM), the full width at half-maximum of the output signal is efficiently compressed 30% more than the current OPM. Finally, the improvements of the MZI output signal by the PPM scheme are in accord with the experimental results.

Lowering The Bit‐Energy of Electro‐Optic Modulators Via Polarization‐Phase Modulation in Thin‐Film BaTiO3 Ferroelectric Crystal Waveguide

“…In this special MZI-type intensity modulator as shown in Figure 1, if G x is the gap between two electrodes in x-direction and Γ 2D is the 2D optic-electrical field interaction efficiency of the embedded waveguide-electrode structure, the half-wave-voltage (V 𝜋 ) at 𝜆 = 1550 nm for both PPM and OPM schemes can be defined as [34] V…”

“…According to Equation (1), we know the maximum scope of the optical phase transfer function under the PPM scheme is much larger than that of OPM scheme, and the output signal can have a higher optical phase transfer efficiency than the current OPM scheme. [34] 3. Theories of BaTiO 3 Thin Film waveguide-based MZI-Type EO Modulators…”

“…Since the modulation process shown in Figure 1 is based on the simultaneous changes of phase and polarization of the light wave ($${\hat{E}}_{\mathrm{2}}$$), it is called polarization‐phase modulation (PPM) scheme. [ 34 ] Figure 1b shows the polarization state evolution of $${\hat{E}}_{\mathrm{2}}$$ at the output with the $${{\Delta}}{\phi }_m$$ caused by the modulated birefringence for a half‐wave modulation. Since the wavefront continuously changes from the right 45° angled linear polarization through various ellipse polarization states to the left 45° angled linear polarization in the first half‐wave optical modulation, it actually presents an optical spin behavior broadly observed in the modern emerging front areas such as crystal optics, integrated optics, as well as in plasmonics.…”

“…[31][32][33] Very recently, we discussed the highly efficient EO modulation method-phase-polarization modulation (PPM) for the thin-film caxis BaTiO 3 waveguide-based modulator and also demonstrated the crucial role of the PPM scheme in increasing the slope of optical phase transfer function of an MZI type intensity EO modulator. [34] In this work, we first analyze the dynamic-polarization interference process of a thin-film BaTiO 3 waveguide-based MZI type EO intensity modulator mechanism under the PPM mechanism, investigate the intrinsic relationships between the slope of optical phase transfer function and the electric-to-optical signal energy transition efficiency and clarifies the principle of PPM mechanism to reduce the half-wave voltage (V 𝜋 ). Then, a theoretical model of equivalent half-wave voltage (V e𝜋 ) of the modulator is established, and a new theoretical model of BE is defined based on it, and then the principle of the PPM mechanism to reduce bit energy is clarified.…”

“…[ 31–33 ] Very recently, we discussed the highly efficient EO modulation method‐phase‐polarization modulation (PPM) for the thin‐film c‐axis BaTiO 3 waveguide‐based modulator and also demonstrated the crucial role of the PPM scheme in increasing the slope of optical phase transfer function of an MZI type intensity EO modulator. [ 34 ]…”