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

Abstract

Layered 2D graphene oxide (GO) films are integrated with micro‐ring resonators (MRRs) to experimentally demonstrate enhanced nonlinear optics. Both uniformly coated (1−5 layers) and patterned (10−50 layers) GO films are integrated on complementary‐metal‐oxide‐semiconductor (CMOS)‐compatible doped silica MRRs using a large‐area, transfer‐free, layer‐by‐layer GO coating method with precise control of the film thickness. The patterned devices further employ photolithography and lift‐off processes to enable precise control of the film placement and coating length. Four‐wave‐mixing (FWM) measurements for different pump powers and resonant wavelengths show a significant improvement in efficiency of ≈7.6 dB for a uniformly coated device with 1 GO layer and ≈10.3 dB for a patterned device with 50 GO layers. The measurements agree well with theory, with the enhancement in FWM efficiency resulting from the high Kerr nonlinearity and low loss of the GO films combined with the strong light–matter interaction within the MRRs. The dependence of GO's third‐order nonlinearity on layer number and pump power is also extracted from the FWM measurements, revealing interesting physical insights about the evolution of the GO films from 2D monolayers to quasi bulk‐like behavior. These results confirm the high nonlinear optical performance of integrated photonic resonators incorporated with 2D layered GO films.

Transforming silicon into a high performing in tegrated nonlinear photonics platform by integrati on with 2D graphene oxide films

“…Finally, we contrast these results with our previous demonstration of enhanced FWM in doped silica devices integrated with layered GO films [43,44]. In that work the waveguides were very different, having negligible nonlinear absorption and comparatively weak nonlinearity, and so it was perhaps not surprising that the GO layers had a dramatic impact on the nonlinear performance.…”

“…In contrast with the monotonic decrease in n2 with GO layer number, n2 varies non-monotonically with the coupled pulse energy. Note that the variation of n2 is much lower than in our previous FWM experiments using CW light [44], probably due to weaker photo thermal effects induced by picosecond optical pulses having much lower average powers compared to CW light. Since it was difficult to accurately measure the slight change in film thickness and refractive index of GO with the coupled pulse energy during the SPM, we neglected any changes in these parameters in our calculations.…”

“…Among the various 2D materials, GO has received increasing interest due to its ease of preparation as well as the tunability of its material properties [36][37][38][39][40][41]. Previously, we reported GO films with a giant Kerr nonlinearity of about 4 orders of magnitude higher than that of silicon [40,42], and demonstrated significantly enhanced four-wave mixing (FWM) in doped silica waveguides and microring resonators integrated with layered GO films [43,44].…”

Strong third-order Kerr nonlinearity in 2D PdSe2 dichalcogenide films

“…The measured n2 of PdSe2 is ∼ -7.65×10 -16 m 2 /W at an intensity of 17.15 GW/cm 2 . Compared with other 2D materials (Table 1), n2 for PdSe2 is lower than graphene and BP, but still two orders of magnitude higher than bulk silicon [12][13][14], which demonstrates the high potential of PdSe2 as a new optical material for nonlinear photonic applications. Further, like Si-Ge heterostructures, [15] PdSe2 may also offer interesting possibilities for second order nonlinear effects courtesy of its complex anisotropic nonlinear optical characteristics.…”

Graphene oxide films for advanced ultra-flat optical devices and photonic integrated circuits

“…(c) Measured TE and TM polarized insertion losses versus input CW power for GO-coated doped silica waveguides [53]. (d) Photo-thermal reduction of GO in GO-coated microring resonators (MRRs) [54]: (i) power-dependent transmission spectra of a doped silica MRR with a patterned GO film measured using a pump-probe method; (ii) transmission spectra before tuning on and after tuning off high-power pump.…”