A high-performance TE modulator/TM-pass polarizer using selective mode shaping in a VO₂-based side-polished fiber

Abstract

The reversible insulating-to-conducting phase transition (ICPT) of vanadium dioxide (VO2) makes it a versatile candidate for the implementation of integrated optical devices. In this paper, a bi-functional in-line optical device based on a four-layer stack of PMMA/graphene/VO2/graphene deposited on a side-polished fiber (SPF) is proposed. The structure can be employed as an ultra-compact TE modulator or a TM-pass polarizer, operating at 1.55 μm. We show that the ICPT characteristic can be used for polarization-selective mode shaping (PSMS) to manipulate orthogonal modes separately. On the one hand, as an optical modulator, the PSMS is used to modify mode profiles so that the TE mode attenuation is maximized in the off-state (and IL is minimized in the on-state), while the power carried by the TM mode remains unchanged. As a result, a TE modulator with an ultrahigh extinction ratio (ER) of about ER = 165 dB/mm and a very low insertion loss (IL) of IL = 2.3 dB/mm is achieved. On the other hand, the structure can act as a TM-pass polarizer featuring an extremely high polarization extinction ratio (PER) of about PER = 164 dB/mm and a low TM insertion of IL = 3.86 dB/mm. The three-dimensional heat transfer calculation for the ICPT process reveals that the response time of the modulator is in the order of few nanoseconds. Moreover, the required bias voltage of the proposed device is calculated to be as low as 1.1 V. The presented results are promising a key step towards the realization of an integrated high-performance in-line modulator/polarizer.

Circularly Polarized Manipulations with VO2‐Doped Dielectric Electromagnetically Induced Transparency and Absorption

“…As a thermally induced phase‐changing material with superior performance, VO 2 has been widely applied to enhance the reconfigurability of the devices, [ 36,37 ] particularly in the manipulation of absorption characteristics [ 51,52 ] starting a transition from the insulator to the metal around 340 K, the generalized Drude model is introduced depicted as Equation (9) to describe the dielectric permittivity. [ 39,40,53 ] $$\begin{equation}\varepsilon (\omega ) = {\varepsilon _\infty } - \frac{{\omega _p^2}}{{\omega (\omega + {\rm{j}}{\omega _d})}}\end{equation}$$when ω → ∞ , ε = ε ∞ = 12 is a steady‐state constant, ω is the angular frequency, ω p and δ respectively represent plasma frequency and the collision frequency, ω p = ( σ (VO 2 )/ σ 0 ) ω p 2 ( σ ), σ 0 = 3×10 5 S m −1 , ω p 2 ( σ 0 ) = 1.40×10 15 S m −1 .…”

“…As a thermally induced phase-changing material with superior performance, VO 2 has been widely applied to enhance the recon-figurability of the devices, [36,37] particularly in the manipulation of absorption characteristics [51,52] starting a transition from the insulator to the metal around 340 K, the generalized Drude model is introduced depicted as Equation ( 9) to describe the dielectric permittivity. [39,40,53]…”

High-performance Mach–Zehnder modulator using tailored plasma dispersion effects in an ITO/graphene-based waveguide

“…Graphene is a two-dimensional (2D) sheet of carbon atoms arranged in a honeycomb lattice that exhibits unique electrical, mechanical, thermal and optical properties 23 . The superb optical characteristics of graphene have made it an amazing choice for various applications such as photodetectors 24 , 25 , logic gates 26 , 27 , polarizers 15 , 28 , plasmonic tweezers 29 , isolators 30 , mode-locked lasers 31 , 32 , switches and modulators 13 , 33 – 37 . The complementary metal-oxide-semiconductor (CMOS) compatibility and great tenability of graphene are of exceptional importance for optical modulators.…”

Design and Analysis of a Polarization-Insensitive VO2/Graphene Optical Modulator Using a 3D Heat Transfer Method

“…Therefore, it is appealing to replace the noble metallic electrodes with the graphene sheets. 5,23 Graphene is a two-dimensional (2D) material containing carbon atoms arranged in a honeycomb lattice. Graphene is known as the miracle material because it exhibits unique electrical, mechanical, and optical characteristics.…”