Fig. 1. Sketch of the proposed structure. (a) Cold cavity. (b) Cavity with gain. (c) Emission spectrum of the dipole source. (d) Real part of refractive index of the gain region. (e) Imaginary part of refractive index of the gain region.

Fig. 2. Output spectrum and integrated intensity of the laser from cold cavity analysis. In (a) and (b), the density of scatters is 2.3 and 73.1  μm−3, respectively. (c) Average intensity received by an inner and outer monitor versus density of scatters.

Fig. 3. Intensity distribution for different resonance modes from cold cavity analysis; (a)–(d) correspond to mode resonance wavelength of 0.537, 0.562, 0.571, and 0.615 μm, respectively, as M1–M4 marked in Fig. 2(a).

Fig. 4. Lasing spectra from four different monitoring positions; (a)–(d) correspond to the monitor position of C1–C4, respectively. Taking center of the core as origin of coordinate, positions of C1–C4 are (0 μm, 6 μm), (6 μm, 0 μm), (0 μm, 6 μm), and (−6  μm, 0 μm), respectively. The thick/thin curves correspond to the case of with/without the consideration of gain. For clarity, intensity of the thin curves is enlarged 20 times.

Fig. 5. Output of the laser with an inserted nanoparticle. (a), (c), and (e) are the spectra; (b), (d), and (f) are the intensity distribution for the nanoparticle sited at positions (0 μm, 5 μm), (5 μm, 0 μm), and (2.5 μm, 2.5 μm); (g)/(h) is the mapping of peak intensity/wavelength of output when position of the inserted nanoparticle varies.