High-Q, low-mode-volume microsphere-integrated Fabry–Perot cavity for optofluidic lasing applications
We develop a hybrid optofluidic microcavity by placing a microsphere with a diameter ranging from 1 to 4 μm in liquid-filled plano-plano Fabry–Perot (FP) cavities, which can provide an extremely low effective mode volume down to 0.3–5.1 μm3 while maintaining a high Q-factor up to 1×104–5×104 and a finesse of ～2000. Compared to the pure plano-plano FP cavities that are known to suffer from the lack of mode confinement, diffraction, and geometrical walk-off losses as well as being highly susceptible to mirror misalignment, our microsphere-integrated FP (MIFP) cavities show strong optical confinement in the lateral direction with a tight mode radius of only 0.4–0.9 μm and high tolerance to mirror misalignment as large as 2°. With the microsphere serving as a waveguide, the MIFP is advantageous over a fiber-sandwiched FP cavity due to the open-cavity design for analytes/liquids to interact strongly with the resonant mode, the ease of assembly, and the possibility to replace the microsphere. In this work, the main characteristics of the MIFP, including Q-factor, finesse, effective mode radius and volume, and their dependence on the surrounding medium’s refractive index, mirror spacing, microsphere position inside the FP cavity, and mirror misalignment, are systematically investigated using a finite-element method. Then, by inserting dye-doped polystyrene microspheres of various sizes into the FP cavity filled with water, we experimentally realize single-mode MIFP optofluidic lasers that have a lasing threshold as low as a few microjoules per square millimeter and a lasing spot radius of only ～0.5 μm. Our results suggest that the MIFP cavities provide a promising technology platform for novel photonic devices and biological/chemical detection with ultra-small detection volumes.
基金项目：National Science Foundation (NSF)10.13039/100000001 (DBI-1451127, ECCS-1607250); International Postdoctoral Exchange Fellowship Program (20160007).
Yipei Wang：Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
Qiushu Chen：Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
Yu-Cheng Chen：Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
Xuzhou Li：Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
Limin Tong：State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
Xudong Fan：Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
【1】X. Fan, and I. M. White, “Optofluidic microsystems for chemical and biological analysis,” Nat. Photonics 5 , 591–597 (2011).
【2】X. Fan, and S. H. Yun, “The potential of optofluidic biolasers,” Nat. Methods 11 , 141–147 (2014).
【3】H.-J. Moon, Y.-T. Chough, and K. An, “Cylindrical microcavity laser based on the evanescent-wave-coupled gain,” Phys. Rev. Lett. 85 , 3161–3164 (2000).
【4】J. Schafer, J. Mondia, R. Sharma, Z. Lu, A. Susha, A. Rogach, and L. Wang, “Quantum dot microdrop laser,” Nano Lett. 8 , 1709–1712 (2008).
【5】Y. Sun, S. I. Shopova, C.-S. Wu, S. Arnold, and X. Fan, “Bioinspired optofluidic FRET lasers via DNA scaffolds,” Proc. Natl. Acad. Sci. USA 107 , 16039–16042 (2010).
【6】Y. Sun, and X. Fan, “Distinguishing DNA by analog-to-digital-like conversion by using optofluidic lasers,” Angew. Chem. Int. Ed. 51 , 1236–1239 (2012).
【7】Q. Chen, X. Zhang, Y. Sun, M. Ritt, S. Sivaramakrishnan, and X. Fan, “Highly sensitive fluorescent protein FRET detection using optofluidic lasers,” Lab Chip 13 , 2679–2681 (2013).
【8】S. Nizamoglu, M. C. Gather, and S. H. Yun, “All-biomaterial laser using vitamin and biopolymers,” Adv. Mater. 25 , 5943–5947 (2013).
【9】A. Joná?, M. Aas, Y. Karadag, S. Manio?lu, S. Anand, D. McGloin, H. Bayraktar, and A. Kiraz, “In vitro and in vivo biolasing of fluorescent proteins suspended in liquid microdroplet cavities,” Lab Chip 14 , 3093–3100 (2014).
【10】M. Humar, A. Dobravec, X. Zhao, and S. H. Yun, “Biomaterial microlasers implantable in the cornea, skin, and blood,” Optica 4 , 1080–1085 (2017).
【11】S. Balslev, and A. Kristensen, “Microfluidic single-mode laser using high-order Bragg grating and antiguiding segments,” Opt. Express 13 , 344–351 (2005).
【12】Z. Li, Z. Zhang, T. Emery, A. Scherer, and D. Psaltis, “Single mode optofluidic distributed feedback dye laser,” Opt. Express 14 , 696–701 (2006).
【13】M. Gersborg-Hansen, and A. Kristensen, “Tunability of optofluidic distributed feedback dye lasers,” Opt. Express 15 , 137–142 (2007).
【14】G. Aubry, Q. Kou, J. Soto-Velasco, C. Wang, S. Meance, J. J. He, and A. M. Haghiri-Gosnet, “A multicolor microfluidic droplet dye laser with single mode emission,” Appl. Phys. Lett. 98 , 111111 (2011).
【15】M. C. Gather, and S. H. Yun, “Single-cell biological lasers,” Nat. Photonics 5 , 406–410 (2011).
【16】Y. Yang, A. Q. Liu, L. Lei, L. K. Chin, C. D. Ohl, Q. J. Wang, and H. S. Yoon, “A tunable 3D optofluidic waveguide dye laser via two centrifugal Dean flow streams,” Lab Chip 11 , 3182–3187 (2011).
【17】M. Humar, M. C. Gather, and S. H. Yun, “Cellular dye lasers: lasing thresholds and sensing in a planar resonator,” Opt. Express 23 , 27865–27879 (2015).
【18】W. Wang, C. Zhou, T. Zhang, J. Chen, S. Liu, and X. Fan, “Optofluidic laser array based on stable high-Q Fabry–Perot microcavities,” Lab Chip 15 , 3862–3869 (2015).
【19】Q. Chen, Y. C. Chen, Z. Zhang, B. Wu, R. Coleman, and X. Fan, “An integrated microwell array platform for cell lasing analysis,” Lab Chip 17 , 2814–2820 (2017).
【20】Y. C. Chen, Q. Chen, T. Zhang, W. Wang, and X. Fan, “Versatile tissue lasers based on high-Q Fabry–Perot microcavities,” Lab Chip 17 , 538–548 (2017).
【21】C.-Y. Gong, Y. Gong, W.-L. Zhang, Y. Wu, Y.-J. Rao, G.-D. Peng, and X. Fan, “Fiber optofluidic microlaser with lateral single mode emission,” IEEE J. Sel. Top. Quantum Electron. 24 , 0900206 (2018).
【22】M. Humar, and S. H. Yun, “Intracellular microlasers,” Nat. Photonics 9 , 572–576 (2015).
【23】P. R. Dolan, G. M. Hughes, F. Grazioso, B. R. Patton, and J. M. Smith, “Femtoliter tunable optical cavity arrays,” Opt. Lett. 35 , 3556–3558 (2010).
【24】D. Hunger, T. Steinmetz, Y. Colombe, C. Deutsch, T. W. H?nsch, and J. Reichel, “A fiber Fabry–Perot cavity with high finesse,” New J. Phys. 12 , 065038 (2010).
【25】A. Muller, E. B. Flagg, J. R. Lawall, and G. S. Solomon, “Ultrahigh-finesse, low-mode-volume Fabry–Perot microcavity,” Opt. Lett. 35 , 2293–2295 (2010).
【26】A. A. Trichet, P. R. Dolan, D. James, G. M. Hughes, C. Vallance, and J. M. Smith, “Nanoparticle trapping and characterization using open microcavities,” Nano Lett. 16 , 6172–6177 (2016).
【27】S.-S. Wang, J. Fu, M. Qiu, K.-J. Huang, Z. Ma, and L.-M. Tong, “Modeling endface output patterns of optical micro/nanofibers,” Opt. Express 16 , 8887–8895 (2008).
【28】Z. Chen, A. Taflove, and V. Backman, “Photonic nanojet enhancement of backscattering of light by nanoparticles: a potential novel visible-light ultramicroscopy technique,” Opt. Express 12 , 1214–1220 (2004).
【29】X. Li, Z. Chen, A. Taflove, and V. Backman, “Optical analysis of nanoparticles via enhanced backscattering facilitated by 3-D photonic nanojets,” Opt. Express 13 , 526–533 (2005).
【30】Z. Chen, X. Li, A. Taflove, and V. Backman, “Backscattering enhancement of light by nanoparticles positioned in localized optical intensity peaks,” Appl. Opt. 45 , 633–638 (2006).
【31】A. Kapitonov, and V. Astratov, “Observation of nanojet-induced modes with small propagation losses in chains of coupled spherical cavities,” Opt. Lett. 32 , 409–411 (2007).
【32】A. Heifetz, S. C. Kong, A. V. Sahakian, A. Taflove, and V. Backman, “Photonic nanojets,” J. Comput. Theor. Nanosci. 6 , 1979–1992 (2009).
【33】A. Fox, and T. Li, “Modes in a maser interferometer with curved and tilted mirrors,” Proc. IEEE 51 , 80–89 (1963).
【34】K. Srinivasan, M. Borselli, O. Painter, A. Stintz, and S. Krishna, “Cavity Q, mode volume, and lasing threshold in small diameter AlGaAs microdisks with embedded quantum dots,” Opt. Express 14 , 1094–1105 (2006).
【35】A. G. Fox, and T. Li, “Resonant modes in a maser interferometer,” Bell Labs Tech. J. 40 , 453–488 (1961).
【36】H. Kogelnik, and T. Li, “Laser beams and resonators,” Appl. Opt. 5 , 1550–1567 (1966).
【37】J. Arnaud, A. Saleh, and J. Ruscio, “Walk-off effects in Fabry–Perot diplexers,” IEEE Trans. Microw. Theory. Tech. 22 , 486–493 (1974).
【38】A. E. Siegman, Lasers (University Science Books, 1986), pp 428–430.
【39】S. M. Buck, H. Xu, M. Brasuel, M. A. Philbert, and R. Kopelman, “Nanoscale probes encapsulated by biologically localized embedding (PEBBLEs) for ion sensing and imaging in live cells,” Talanta 63 , 41–59 (2004).
【40】S. Yang, and V. N. Astratov, “Photonic nanojet-induced modes in chains of size-disordered microspheres with an attenuation of only 0.08?dB per sphere,” Appl. Phys. Lett. 92 , 261111 (2008).
【41】K. W. Allen, A. Darafsheh, F. Abolmaali, N. Mojaverian, N. I. Limberopoulos, A. Lupu, and V. N. Astratov, “Microsphere-chain waveguides: focusing and transport properties,” Appl. Phys. Lett. 105 , 021112 (2014).
【42】F. Abolmaali, A. Brettin, A. Green, N. I. Limberopoulos, A. M. Urbas, and V. N. Astratov, “Photonic jets for highly efficient mid-IR focal plane arrays with large angle-of-view,” Opt. Express 25 , 31174–31185 (2017).
【43】A. Martinez, and S. Yamashita, “Multi-gigahertz repetition rate passively modelocked fiber lasers using carbon nanotubes,” Opt. Express 19 , 6155–6163 (2011).
【44】J. M. Gérard, D. Barrier, J. Y. Marzin, R. Kuszelewicz, L. Manin, E. Costard, V. Thierry-Mieg, and T. Rivera, “Quantum boxes as active probes for photonic microstructures: the pillar microcavity case,” Appl. Phys. Lett. 69 , 449–451 (1996).
Xiaoqin Wu, Yipei Wang, Qiushu Chen, Yu-Cheng Chen, Xuzhou Li, Limin Tong, and Xudong Fan, "High-Q, low-mode-volume microsphere-integrated Fabry–Perot cavity for optofluidic lasing applications," Photonics Research 7(1), 50-60 (2019)