Two-Photon Excitation of Silicon-Vacancy Centers in Nanodiamonds for All-Optical Thermometry with a Noise Floor of 6.6 mK·Hz^–1/2

Abstract

In this paper, we introduce ultrasensitive all-optical nanothermometry using high figure-of-merit nanodiamonds with silicon-vacancy (SiV) centers. In contrast to the commonly used single-photon process, we have adopted a two-photon approach to achieve efficient excitation of SiV centers in nanodiamonds. Based on the developed intensity-projected scheme, we have experimentally achieved a noise floor of 6.6 mK•Hz −1/2 using nanodiamonds. This serves as a new record of temperature resolution in the relevant field. Particularly, this simplified method allows us to reflect the temperature-induced spectral shift without wavelength scanning via a spectrometer. Furthermore, we demonstrate that the two-photon excitation of SiV centers has been thermally activated, as indicated by an elevated fluorescence intensity accompanied by a temperature increase. Our findings offer an opportunity for harnessing SiV-based nanothermometry in an easy-to-use manner and open the road for the development of practical applications in complicated environments such as living cells.

Novel Nanocomposites for Luminescent Thermometry with Two Different Modalities

“…These results align well with previous studies on optical thermometry using SiV color centers in diamond nanocrystals, conducted over a similar temperature range. To estimate the SiV sensor sensitivity, with an integration time of 10 s, we were able to detect temperature changes as small as 0.2 K. This level of sensitivity aligns with the reported critical optical temperature sensing threshold for a similar integration time reported in [ 16 , 21 , 25 , 26 ].…”

Luminescence Thermometry Beyond the Biological Realm

“…A limited number of studies have also explored the use of NV center excited state lifetimes for thermometry, ,, providing another all-optical approach, which is discussed further in Section (Time-Resolved Measurements). More recently, other color centers beyond NV centers have gained traction for thermometry, such as silicon vacancy (SiV), − germanium vacancy (GeV), − tin vacancy (SnV), and magnesium vacancy (MgV) centers, all of which enable all-optical thermometry. A diverse range of physical mechanisms gives rise to the temperature-dependent emission signals used for color center-based thermometry.…”

“…Temperature-dependent zero-field splitting and changes to the ZPL peak position or width are common metrics for these other color centers in addition to NV centers. Other signals, such as anti-Stokes to Stokes photoluminescence intensity ratios whose temperature dependence originates from thermally activated anti-Stokes excitation or the emission intensity resulting from thermally activated two-photon excitation, have also been employed.…”

Fiber-Based Ratiometric Optical Thermometry with Silicon Vacancy in Microdiamonds

“…16 group IV color centers such as germanium-vacancy (GeV), silicon-vacancy (SiV), lead-vacancy, tin-vacancy, etc., are some of the most common diamond color centers, owing to their compelling photophysical properties. 17 Temperature changes alter various spectral characteristics of diamond color centers, such as zero phonon line (ZPL) wavelength, 18 ZPL line width, 19 photoluminescence (PL) intensity, 20 shift in optically detected magnetic resonance (ODMR) spectra, 21 etc., which are then analyzed to set up the correlation between the observable and temperature. However, most of these methods require postprocessing of the acquired data or take a longer time to acquire spectral features, which can lead to slower temperature measurements.…”