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(a) Experimental setup employing a NPBS for homodyne measurements. The carrier-generating 780 nm cw field is modulated with an AOM to enable phase sensitive detection with an APD and a lock-in amplifier. A half-wave plate is used to ensure that the linearly polarized scanning cw laser and cavity mode are copolarized, while a microscope objective (Obj.) focuses incident light onto the sample. A scanning electron micrograph of the L3 cavity is shown in the inset. (b) Theoretical and (c) experimentally obtained cavity reflectivity spectra with and without a resonant QD. The calculated difference between the two spectra in each case is also given. Theoretical plots ignore the effects of spectral wandering and blinking. Experimental spectra were obtained in cross-polarized reflectivity measurements without the use of phase-sensitive techniques as in Ref. 10.
DR spectra (offset) obtained at different sample temperatures with a 6 nW tunable cw laser and a 20 nW 780 nm laser modulated at 20 kHz. Temperature variation serves to tune the QD through the cavity resonance. The dotted curve is a fit of the analytical expression for to the 28.7 K trace. The two dashed lines are guides to the eye to show the anticrossing of the polariton peaks corresponding roughly to the minimum values in each spectrum.
Signal strengths in DR spectra as a function of 780 nm laser power for a QD resonant with a PCC. The tunable cw laser is kept at 20 nW and the 780 nm laser is modulated at 10 kHz. The signal is taken as the difference between maximum and minimum values in each DR spectrum and is shown to saturate at higher powers. Inset: DR spectra for 780 nm laser powers of 5 nW and 60 nW.
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