Research ArticleChemistry

Dual-color single-mode lasing in axially coupled organic nanowire resonators

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Science Advances  14 Jul 2017:
Vol. 3, no. 7, e1700225
DOI: 10.1126/sciadv.1700225
  • Fig. 1 Mutual mode selection concept in the coupled NW resonant cavities.

    Sketch of the multimode lasing from separate A and B NWs (top and middle) and dual-color single-mode lasing from axially coupled A + B NW cavities (bottom), where the NWs serve as both the laser source and the mode filter for each other.

  • Fig. 2 Preparation of the OPV-A and OPV-B NW lasers.

    (A and E) PL images of the OPV-A and OPV-B NWs under UV (330 to 380 nm) excitation. Scale bars, 10 μm. (B and F) SEM images of the typical OPV-A and OPV-B NWs. Scale bars, 5 μm. (C and G) TEM images of the individual OPV-A and OPV-B NWs. Scale bars, 500 nm. Inset: SAED patterns of the NWs. (D and H) Multimode lasing spectra from the OPV-A and OPV-B NWs, excited with a pulsed laser (400 nm). Insets: Corresponding PL images of the OPV-A and OPV-B NWs above the lasing threshold. Scale bars, 5 μm. a.u., arbitrary units.

  • Fig. 3 Realization of single-mode lasing in heterogeneously coupled NWs.

    (A) PL image of the axially coupled heterogeneous NWs under uniform excitation with the UV band (330 to 380 nm) of a mercury lamp. Scale bar, 10 μm. (B) False-colored SEM image of the coupled NWs. Scale bar, 2 μm. Inset: Magnified view of the gap region. Scale bar, 1 μm. (C and D) Transition of the lasing spectra of the typical OPV-A and OPV-B NWs from multimode to single mode when they are coupled with each other. Insets: Corresponding PL images of the individual OPV-A and OPV-B NWs and the coupled NW pairs under laser excitation. Scale bars, 5 μm. (E and F) Pump power–dependent PL intensities of the isolated and heterogeneously coupled NWs shown in (C) and (D). The axially coupled heterogeneous NW cavity structure provides an effective mode selection effect while avoiding the significant increase of the lasing threshold.

  • Fig. 4 Mechanism of mode selection in the axially coupled heterogeneous NW resonator system.

    (A) Schematic illustration of the axially coupled heterogeneous cavities. ρ represents end-facet reflectivity of the single NW; ρeff represents effective reflectivity of the lasing cavity at the right end facet. (B) Effective reflectivity of the lasing cavity at the end facet coupled with the filter cavity, with the end-facet reflectivity of the isolated NW added as a comparison. (C) Threshold gain of the cavity modes in the active NW with and without the coupling of the passive NW. The modulated end-facet reflectivity and threshold gain demonstrate the mode selection mechanism in the axially coupled heterogeneous NW cavity system.

  • Fig. 5 Controlled outcoupling of the dual-color single-mode lasing from the coupled NW resonant cavities.

    (A) Simulated field intensity distribution of two types of highest-Q lasing modes in the axially coupled heterogeneous NW cavities, which manifests the mutual mode modulation effect in the coupled cavity. (B) Lasing emission spectra of the axially coupled heterogeneous NW cavities under laser excitation at different positions. The dual-color single-mode lasing was realized by pumping the heterogeneously coupled organic NW resonators in whole. Scale bar, 10 μm. (C) Spatially resolved PL spectra collected from three different ports: the intercavity gap of the heterogeneously coupled cavity system (O2) and the end facets of OPV-A (O1) and OPV-B (O3). Scale bar, 5 μm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700225/DC1

    section S1. Synthesis procedure and luminescence properties of the model compounds

    section S2. Structural characterizations and lasing measurements of the isolated OPV-A and OPV-B NWs

    section S3. Construction of the axially coupled heterogeneous NW resonators with effective mode modulation

    section S4. Numerical simulation of the effective refractivity and threshold gain

    fig. S1. The synthetic route of compound OPV-A.

    fig. S2. The synthetic route of compound OPV-B.

    fig. S3. Normalized fluorescence spectra of the OPV-A and OPV-B powders.

    fig. S4. Absolute fluorescence quantum yields (Φ) of OPV-A and OPV-B powders.

    fig. S5. XRD patterns of OPV-A and OPV-B NWs and powder samples.

    fig. S6. Optical waveguiding properties of OPV-A and OPV-B NWs.

    fig. S7. Schematic illustration of the homebuilt setup for optical characterization.

    fig. S8. Microcavity effects of uncoupled NWs.

    fig. S9. Schematic diagram of the fabrication process of the axially coupled heterogeneous NWs.

    fig. S10. Controllable fabrication of the axially coupled heterogeneous NW cavities.

    fig. S11. Three-dimensional numerical simulation of the output field from the NW end facet.

    fig. S12. Influence of gap distance on the mode modulation.

    fig. S13. Schematic diagram of the construction strategy of the desired gap distance for axially coupled heterogeneous NW resonators.

    fig. S14. Coupling effect of axially coupled heterogeneous NW cavities.

    fig. S15. Evolution of the emission spectra with the increase of pump power for isolated and heterogeneously coupled NWs.

    fig. S16. Lasing characterization of the OPV-B NW coupled with OPV-A NWs of different lengths.

    fig. S17. Lasing characterization of the axially coupled heterogeneous NWs with varying gap distances.

    fig. S18. Theory model.

    References (5458)

  • Supplementary Materials

    This PDF file includes:

    • section S1. Synthesis procedure and luminescence properties of the model compounds
    • section S2. Structural characterizations and lasing measurements of the isolated OPV-A and OPV-B NWs
    • section S3. Construction of the axially coupled heterogeneous NW resonators with effective mode modulation
    • section S4. Numerical simulation of the effective refractivity and threshold gain
    • fig. S1. The synthetic route of compound OPV-A.
    • fig. S2. The synthetic route of compound OPV-B.
    • fig. S3. Normalized fluorescence spectra of the OPV-A and OPV-B powders.
    • fig. S4. Absolute fluorescence quantum yields (Φ) of OPV-A and OPV-B powders.
    • fig. S5. XRD patterns of OPV-A and OPV-B NWs and powder samples.
    • fig. S6. Optical waveguiding properties of OPV-A and OPV-B NWs.
    • fig. S7. Schematic illustration of the homebuilt setup for optical characterization.
    • fig. S8. Microcavity effects of uncoupled NWs.
    • fig. S9. Schematic diagram of the fabrication process of the axially coupled heterogeneous NWs.
    • fig. S10. Controllable fabrication of the axially coupled heterogeneous NW cavities.
    • fig. S11. Three-dimensional numerical simulation of the output field from the NW end facet.
    • fig. S12. Influence of gap distance on the mode modulation.
    • fig. S13. Schematic diagram of the construction strategy of the desired gap distance for axially coupled heterogeneous NW resonators.
    • fig. S14. Coupling effect of axially coupled heterogeneous NW cavities.
    • fig. S15. Evolution of the emission spectra with the increase of pump power for isolated and heterogeneously coupled NWs.
    • fig. S16. Lasing characterization of the OPV-B NW coupled with OPV-A NWs of different lengths.
    • fig. S17. Lasing characterization of the axially coupled heterogeneous NWs with varying gap distances.
    • fig. S18. Theory model.
    • References (5458)

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