Abstract
We demonstrate a new type of photonic crystal nanolaser incorporated into a microfluidic chip, which is fabricated by multilayer soft lithography. Experimentally, room-temperature continuous-wave lasing operation was achieved by integrating a photonic crystal nanocavity with a microfluidic unit, in which the flow medium both enhances the rate of heat removal and modulates the refractive index contrast. Furthermore, using the proposed system, dynamic modulation of the resonance wavelength and far-field radiation pattern can be achieved by introducing a bottom reflector across which various fluids with different refractive indices are forced to flow. In particular, by maintaining a gap between the reflector and the cavity equal to the emission wavelength, highly efficient unidirectional emission can be obtained. The proposed nanolasers are ideal platforms for highfidelity biological and chemical detection tools in micro-total-analytical or lab-on-a-chip systems.
Highlights
Active photonic crystal (PhC) light emitters based on wavelength-scale cavities have been of particular interest to laser physics and quantum information researchers due to their potential applications in efficient single photon sources and ultra-low-threshold lasers.[1, 2, 3, 4] highly divergent far-field emission inherent to the wavelength-scale small nature means that these systems suffer from poor vertical out-coupling efficiency.[5]
The results show that the directional beaming condition is preserved for these multiple-wavelength gap sizes; for 2λ (3λ ) gap case, ∼ 36 % (∼ 31 %) of the total emission power can be collected within the numerical aperture of 0.4 (θ ≤ 23.6◦) in the glass
Divergent far-field emission and poor thermal characteristics have been daunting problems limiting the utility of PhC nanocavities in thin dielectric membranes
Summary
Active photonic crystal (PhC) light emitters based on wavelength-scale cavities have been of particular interest to laser physics and quantum information researchers due to their potential applications in efficient single photon sources and ultra-low-threshold lasers.[1, 2, 3, 4] highly divergent far-field emission inherent to the wavelength-scale small nature means that these systems suffer from poor vertical out-coupling efficiency.[5]. A fluid is forced to flow in the vicinity of the PhC cavity, thereby modulating the effective optical thickness of the gap, and allowing dynamic control of the far-field pattern.[10] The large ranges of index modulation that are made possible using fluid flow enable real-time tunability and reconfigurability. We show that continuous flow of a fluid (water in the present experiments) in the vicinity of the PhC cavity improves the thermal diffusion, enabling RT-CW operation to be achieved. The same principle can be applied to high-fidelity refractive index sensors[13] that can detect a specific chemical and biological species
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