1 3 DOI 10.1007/s00340-014-5958-z Appl. Phys. B (2015) 118:93–100 Lasing behavior modulation in a layered cylindrical microcavity Panlin Li · Chunxiang Xu · Mingming Jiang · Jun Dai · Jitao Li · Junfeng Lu Received: 6 July 2014 / Accepted: 30 October 2014 / Published online: 12 November 2014 © Springer-Verlag Berlin Heidelberg 2014 have been proposed and demonstrated. Among these alter- natives, the WGM microcavities have attracted increasing research attention in recent years due to their low optical losses and tight mode confinement. In such resonators, light wave is guided by continuous total internal reflection (TIR) at the cavity boundary. When the round trip optical path length is equal to an integer number of the light wave- length, constructive interference of light takes place inside the WGM microcavity. WGM lasing from various geometries, including microspheres [13, 14], microrings [15, 16], and micro- cylinders [17, 18], have been reported. For spherical resonators such as microdroplets, laser emission can be generated by embedding gain materials into such cavity [13], while for the microring cavities, the WGM lasing is obtained by coating a polymer gain layer around the opti- cal fiber [16]. However, the difficulty in manipulation and mechanical fragility largely hinder their practical applica- tions. Obviously, the layered cylindrical microcavity con- sisting of a fused-silica capillary filled with a high refrac- tive index (RI) liquid might be favorable for WGM lasing in terms of both simpler fabrication and better mechani- cal stability. Moreover, capillary cavities are easier to be aligned into arrays and readily compatible with microflu- idic systems [19]. Besides the high quality performance, laser modula- tion capability is also required in the application of mod- ern technologies such as tunable optical sources and opti- cal communication. Generally, laser modulation has been realized by adjusting optical cavity size and shape [20, 21], but mechanical control is inaccurate and impractical for real applications. Another possible scheme indicated by the previous studies [22–24] is using coupled asymmetric microcavity via the Vernier effect. Compared with tradi- tional approaches, the capillary cavities can easily integrate Abstract Optically pumped lasing behaviors modulation was realized in a layered cylindrical microcavity dye laser formed by rhodamine 6G-doped quinoline in a capillary. By inserting an optical fiber into the cylindrical microcav- ity, whispering gallery modes were successfully suppressed and a new kind of waveguide mode lasing was obtained. The lasing characteristics and resonance mechanism of the two configurations were systematically discussed in both experiment and theoretical calculation. Moreover, the time domain and frequency domain finite element methods were performed and found that with the adjustment of the central fiber, the transition of resonant mode from WGMs to wave- guide modes can be achieved. 1 Introduction Optical microresonators have proven to be highly important for both fundamental physics investigation of light–matter interaction [1] and potential applications such as efficient microlaser, optical filters, modulators, and miniature sen- sors [2–5]. To date, various types of microresonators, such as Fabry–Pérot cavity [6, 7], random cavity [8], plasmonic cavity [9], distributed feedback (DFB) resonator [10], as well as whispering gallery mode (WGM) cavity [11, 12], P. Li · C. Xu (*) · J. Dai · J. Li · J. Lu State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China e-mail: xcxseu@seu.edu.cn M. Jiang State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China