Abstract
The optical absorption coefficient of graphene will change after injecting carriers. Based on this principle, a high-speed double-layer graphene electro-optic modulator with a ring resonator structure was designed in this paper. From the numerical simulations, we designed a modulator. Its optical bandwidth is larger than 130 GHz, the switching energy is 0.358 fJ per bit, and the driven voltage is less than 1.2 V. At the same time, the footprint of the proposed modulator is less than 10 microns squared, which makes the process compatible with the Complementary Metal Oxide Semiconductors (CMOS) process. This will provide the possibility for the on-chip integration of the photoelectric device.
Highlights
Optical modulators are key components for telecommunications and optical interconnections.Researchers have paid a lot of attention and effort to reducing their dimensions and integrating them onto silicon substrates [1].Traditional straight waveguide modulators work due to the plasma dispersion effect: the optical absorption coefficient of silicon losses are modified upon the injection of free carriers [2,3,4]
The light will travel thousands of loops in the ring waveguide; in this way, even a tiny variation of the refractive index may lead to a huge shift of the resonant wavelength, and the intensity of emergent light is modulated
The contact resistance between the graphene film and metal electrode varies with different metal materials and different processes
Summary
Optical modulators are key components for telecommunications and optical interconnections. It is used to produce a π-shift in one of the Mach-Zehnder arms, and the desired intensity modulation is obtained by optical interference As this effect induces small variations of the refractive index, this device still has relatively large dimensions. The light will travel thousands of loops in the ring waveguide; in this way, even a tiny variation of the refractive index may lead to a huge shift of the resonant wavelength, and the intensity of emergent light is modulated Based on this idea, this kind of device can be made in a small size, but the tradeoff is the limited bandwidth of a few GHz that the resonances can offer.
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