Screen-printed graphene tailoring the amplitude of guided wave in the rectangular waveguide for millimeter wave applications

Abstract

Graphene as an optoelectronic material displays unique advantages in the modulation of amplitude and phase of millimeter waves attributed to its high carrier mobility and broadband optoelectronic properties. The electronic properties of graphene are precisely controllable with the screen-printing technique. We herein employed the screen-printed graphene to manipulate the transmission of the guided millimeter waves in a metallic waveguide. The effects of the patterns and sizes of screen-printed graphene on the modulation of guided waves are first investigated and found that the rhombus is the optimal pattern shape in terms of linearly broadband modulation and reflection loss. The advanced screen-printing technique enables tuning the sheet resistance of the graphene from 45 Cd/sq. to 205 Cd/sq. Numerical simulation shows that the maximum transmittance modulation depth of the guided wave is about 20 dB related to the tuning range of the graphene sheet resistance. A millimeter-wave metallic waveguide integrated with screen-printed graphene is fabricated and measured to validate the proposed scenario. The broadband transmittance modulation depth of 4 dB is experimentally observed with reflection loss lower than -15 dB in the full frequency band of 60-75 GHz, which is consistent with simulated results. The guided wave modulation with screen-printed graphene exhibits great opportunities in millimeter wave devices and systems.