Invited Article: Enhanced four-wave mixing in waveguides integrated with graphene oxide

Abstract

We demonstrate enhanced four-wave mixing (FWM) in doped silica waveguides integrated with graphene oxide (GO) layers. Owing to strong mode overlap between the integrated waveguides and GO films that have a high Kerr nonlinearity and low loss, the FWM efficiency of the hybrid integrated waveguides is significantly improved. We perform FWM measurements for different pump powers, wavelength detuning, GO coating lengths, and number of GO layers. Our experimental results show good agreement with theory, achieving up to ∼9.5-dB enhancement in the FWM conversion efficiency for a 1.5-cm-long waveguide integrated with 2 layers of GO. We show theoretically that for different waveguide geometries an enhancement in FWM efficiency of ∼20 dB can be obtained in the doped silica waveguides and more than 30 dB in silicon nanowires and slot waveguides. This demonstrates the effectiveness of introducing GO films into integrated photonic devices in order to enhance the performance of nonlinear optical processes.

Graphene Oxide Waveguide and Micro‐Ring Resonator Polarizers

“…The waveguides were fabricated from high‐index doped silica glass core surrounded by silica via CMOS compatible processes with chemical mechanical polishing (CMP) used as the last step to remove the upper cladding, so as to enable GO film coating on the top surface of the waveguide. GO coating was achieved with a solution‐based method that yielded layer‐by‐layer GO film deposition, as reported previously . Four steps for in situ assembly of monolayer GO films were repeated to construct multilayer GO films on the desired substrate, with the process being highly scalable.…”

“…Recently, we reported large‐area, transfer‐free, and high‐quality GO film coating on integrated waveguides using a solution‐based method with layer‐by‐layer deposition of GO films. Here, we use these techniques to demonstrate GO‐coated integrated waveguide polarizers and polarization‐selective micro‐ring resonators (MRRs) on a CMOS compatible doped silica platform.…”

2D Layered Graphene Oxide Films Integrated with Micro‐Ring Resonators for Enhanced Nonlinear Optics

“…[ 8,25 ] The giant Kerr nonlinear response of 2D layered materials such as graphene, graphene oxide (GO), black phosphorus, and transition metal dichalcogenides (TMDCs) has been widely recognized and exploited to implement diverse nonlinear photonic devices with high performance and new capabilities. [ 25–35 ] In particular, a 6.8 dB enhancement in the FWM CE was reported for a silicon MRR incorporating a monolayer of doped graphene. [ 31 ]…”

“…[ 27,36–39 ] Previously, we reported GO films with a giant Kerr nonlinearity ( n 2 ) of about four orders of magnitude higher than that of silicon, [ 27,40 ] and achieved enhanced FWM CE in GO‐coated doped silica waveguides of up to 6.9 dB for a 1.5 cm‐long waveguide uniformly coated with two layers of GO. [ 29 ] Moreover, GO has a material absorption that is over two orders of magnitude lower than graphene [ 29 ] as well as a large bandgap (2.1−2.4 eV) that yields a low TPA in the telecommunications band. [ 41,42 ] Recently, we achieved highly precise control of the placement, thickness, and length of the GO films coated on integrated photonic devices by using a large‐area, transfer‐free, layer‐by‐layer GO coating method together with standard photolithography and lift‐off processes.…”

Enhanced four-wave mixing in hybrid integrated waveguides with graphene oxide

“…Four wave mixing (FWM), as an important nonlinear optical effect, has been widely explored to realize all-optical signal processing functions such as wavelength conversions, optical logic gates, optical comb generations, and quantum entanglements [4][5][6][7][8][9][10][11]. To date, efficient FWM in telecommunications band has been successfully demonstrated by using silica fibers, III/V material-based semiconductor optical amplifiers (SOAs), integrated photonic devices based on silicon or silicon compounds, polymer composites, chalcogenide devices, and so forth [5,12]. Among them, the integrated photonic devices provide a competitive solution to achieve on-chip processing with compact footprint, high stability, massproducibility, and excellent cost performance [13][14][15][16][17][18][19][20].…”