Enhanced optical Kerr nonlinearity of MoS2 on silicon waveguides
A quasi-two-dimensional layer of MoS2 was placed on top of a silicon optical waveguide to form a MoS2–silicon hybrid structure. Chirped pulse self-phase modulation measurements were carried out to determine the optical Kerr nonlinearity of the structure. The observed increase in the spectral broadening of the optical pulses in the MoS2–silicon waveguide compared with the silicon waveguides indicated that the third-order nonlinear effect in MoS2 is about 2 orders of magnitude larger than that in silicon. The measurements show that MoS2 has an effective optical Kerr coefficient of about 1.1 × 10?16 m2∕W. This work reveals the potential application of MoS2 to enhance the nonlinearity of hybrid silicon optical devices.
基金项目：This work was fully funded by Hong Kong Research Grants Council research project nos. GRF416913, N_CUHK405/12, AoE/P-02/12, CUHK1/CRF/12G. The authors would like to thank Qijie Xie for the technical support.
Ke Xu：Department of Electronic and Information Engineering, Shenzhen Graduate School,Harbin Institute of Technology, Shenzhen, China
Xi Wan：Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China
Jianbin Xu：Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China
Chi Yan Wong：Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China
Hon Ki Tsang：Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China
【1】Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman, and M. S. Strano, “Electronics and optoelectronics of two-dimensional transition metal dichalcogenides,” Nat. Nanotechnol. 7, 699– 712 (2012).
【2】K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically thin MoS2: a new direct-gap semiconductor,” Phys. Rev. Lett. 105, 136805 (2010).
【3】S. Das, H.-Y. Chen, A. V. Penumatcha, and J. Appenzeller, “High performance multilayer MoS2 transistors with scandium contacts,” Nano Lett. 13, 100–105 (2012).
【4】B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, and A. Kis, “Single-layer MoS2 transistors,” Nat. Nanotechnol. 6, 147–150 (2011).
【5】K. Novoselov, A. K. Geim, S. Morozov, D. Jiang, M. Katsnelson, I. Grigorieva, S. Dubonos, and A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature 438, 197–200 (2005).
【6】O. Lopez-Sanchez, D. Lembke, M. Kayci, A. Radenovic, and A. Kis, “Ultrasensitive photodetectors based on monolayer MoS2,” Nat. Nanotechnol. 8, 497–501 (2013).
【7】H. Liu, A.-P. Luo, F.-Z. Wang, R. Tang, M. Liu, Z.-C. Luo, W.-C. Xu, C.-J. Zhao, and H. Zhang, “Femtosecond pulse erbium-doped fiber laser by a few-layer MoS2 saturable absorber,” Opt. Lett. 39, 4591–4594 (2014).
【8】F. Wang, S. Xu, Y. Feng, Y. Li, X. Zhang, Y. Xu, and J. Wang, “Characteristics of saturable absorption of MoS2 films in the visible to near-infrared range,” in Asia Communications and Photonics Conference (Optical Society of America, 2014), paper ATh4B.5.
【9】X. Yin, Z. Ye, D. A. Chenet, Y. Ye, K. O’Brien, J. C. Hone, and X. Zhang, “Edge nonlinear optics on a MoS2 atomic monolayer,” Science 344, 488–490 (2014).
【10】R. Wang, H.-C. Chien, J. Kumar, N. Kumar, H.-Y. Chiu, and H. Zhao, “Third-harmonic generation in ultrathin films of MoS2,” ACS Appl. Mater. Interfaces 6, 314–318 (2013).
【11】Y.-H. Lee, L. Yu, H. Wang, W. Fang, X. Ling, Y. Shi, C.-T. Lin, J.-K. Huang, M.-T. Chang, and C.-S. Chang, “Synthesis and transfer of single-layer transition metal disulfides on diverse surfaces,” Nano Lett. 13, 1852–1857 (2013).
【12】Y.-H. Lee, X.-Q. Zhang, W. Zhang, M.-T. Chang, C.-T. Lin, K.-D. Chang, Y.-C. Yu, J. T.-W. Wang, C.-S. Chang, L.-J. Li, and T.-W. Lin, “Synthesis of large-area MoS2 atomic layers with chemical vapor deposition,” Adv. Mater. 24, 2320–2325 (2012).
【13】S. Najmaei, Z. Liu, W. Zhou, X. Zou, G. Shi, S. Lei, B. I. Yakobson, J.-C. Idrobo, P. M. Ajayan, and J. Lou, “Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers,” Nat. Mater. 12, 754–759 (2013).
【14】A. M. van der Zande, P. Y. Huang, D. A. Chenet, T. C. Berkelbach, Y. You, G.-H. Lee, T. F. Heinz, D. R. Reichman, D. A. Muller, and J. C. Hone, “Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide,” Nat. Mater. 12, 554–561 (2013).
【15】C. Lee, H. Yan, L. E. Brus, T. F. Heinz, J. Hone, and S. Ryu, “Anomalous lattice vibrations of single-and few-layer MoS2,” ACS Nano 4, 2695–2700 (2010).
【16】vC.-C. Shen, Y.-T. Hsu, L.-J. Li, and H.-L. Liu, “Charge dynamics and electronic structures of monolayer MoS2 films grown by chemical vapor deposition,” Appl. Phys. Express 6, 125801 (2013).
【17】R. H. Stolen and C. Lin, “Self-phase-modulation in silica optical fibers,” Phys. Rev. A 17, 1448–1453 (1978).
【18】G. P. Agrawal, Nonlinear Fiber Optics (Academic, 2007).
【19】T. Baehr-Jones, M. Hochberg, C. Walker, E. Chan, D. Koshinz, W. Krug, and A. Scherer, “Analysis of the tuning sensitivity of silicon- on-insulator optical ring resonators,” J. Lightwave Technol. 23, 4215–4221 (2005).
【20】J. T. Robinson, K. Preston, O. Painter, and M. Lipson, “Firstprinciple derivation of gain in high-index-contrast waveguides,” Opt. Express 16, 16659–16669 (2008).
【21】H. Tsang and Y. Liu, “Nonlinear optical properties of silicon waveguides,” Semicond. Sci. Technol. 23, 064007 (2008).
【22】T. Schneider, Nonlinear Optics inTelecommunications (Springer, 2004).
Linghai Liu, Ke Xu, Xi Wan, Jianbin Xu, Chi Yan Wong, and Hon Ki Tsang, "Enhanced optical Kerr nonlinearity of MoS2 on silicon waveguides," Photonics Research 3(5), 206-209 (2015)