Fig. 2: Two-laser photoluminescence excitation spectroscopy.
From: Check-probe spectroscopy of lifetime-limited emitters in bulk-grown silicon carbide
a Experimental sequence. A short (10 μs, 10 μW) high-energy (785 nm) repump laser pulse (‘R’) partially scrambles the charge state of both the environment and the V2 centre. Emission is collected during the ‘check’ block, when two NIR lasers at frequencies f1 and f2 are turned on (approximately resonant with the broad peak in Fig. 1g). b We observe an increase in count rate if the laser frequency difference is equal to Δ = 954(2) MHz, the spacing between the A1 and A2 transitions. A Lorentzian fit obtains an FWHM of 89(9) MHz. c Detected mean count rate per experimental repetition, when the length of the ‘check’ block is set to 5 ms. In most repetitions, the defect is off-resonant with the lasers. When the A1 and A2 transitions coincide with laser frequencies f1 and f2, we observe significant emission (≫1 kHz). Thresholding (dashed line) on the detected counts can be employed to prepare specific (i.e. ‘on resonance’) spectral configurations of the V2 centre.
