Fel0550

We used a CW DPSS laser module with a wavelength of $532\mathrm{nm}$ and a power of approximately $30\mathrm{mW}$ for excitation of the NV ensemble that is optically coupled to the optical fiber. As sketched in Figure 2a, the laser beam is reflected off a dichroic beamsplitter (DBS) with a $550\mathrm{nm}$ longpass characteristic (Thorlabs DMLP550) and focused into the fiber core with a microscope objective with a numerical aperture of NA $=0.25$ . The NV fluorescence is collimated by the same microscope objective, passes through the DBS and a bandpass filterset with a cut-on wavelength of $550\mathrm{nm}$ (Thorlabs FEL0550) and a cut-off wavelength of $750\mathrm{nm}$ (Thorlabs FES0750). This bandpass is tailored to the expected fluorescence spectrum of NV centers in diamond at room temperature [14 (link)] in order to suppress leakage of laser radiation and unwanted fiber fluorescence and thus increase the signal-to-noise ratio of the setup. Measurement of fluorescence intensity and data acquisition is further described in Section 2.2.2.

Tailored non-paraxial 4D fields are analyzed by a fluorescent SAM. For this purpose, the probe, consisting of the monolayer produced on a glass cover slip (refractive index n = 1.33, thickness 170 μm) is placed in the focal plane of the non-paraxial field. Note that the fluorescent molecules are directly irradiated by the light field, thus, the probe is placed with the monolayer at the bottom on its holder (monolayer-glass-order in beam propagation direction, see Fig. 1a). By this, aberration effects occurring when the beam is transmitted trough the cover slip are avoided, as the MO focuses is aberration free in air. Excited fluorescence is observed in transmission, passing through the cover slip. For collecting scattered fluorescence and imaging the fluorescence in the plane of the monolayer (=focal plane) onto a CCD camera (Photometrics CoolSNAP MYO), we apply a high-NA MO (Nikon C-AB Abbe Condenser, ×100, NA = 0.9) in combination with a lens (focal distance: 500 mm). The exciting light field (λ = 532 nm) is filtered in front of the CCD (longpass filter, Thorlabs FEL0550), so that pure fluorescence (λ_fl ~ 594 nm) is observed . Note that noise within recorded fluorescence images is reduced by taking the mean value of ten images and applying background subtraction.

To facilitate imaging of fluorescent saliva, Aedes aegypti were allowed to feed on a solution containing 0.4% rhodamine B and 10% sucrose in water for at least 48 h. The rhodamine B ingested during sugar feeding stains the mosquito body including saliva^{44 (link)}. Imaging was performed using a 532 nm, 5 mW laser (Sparkfun, COM-09906) for illumination, and a 550 nm longpass filter (Thorlabs FEL0550) as an emission filter. Images were acquired using a Basler acA2040-90um camera controlled using Pylon 5 software running on an Ubuntu 18.04 computer (NUC8i7BEH). The camera was equipped with a 100 mm macro lens (Canon macro EF 100 mm f/2.8L)^{25 (link)}. Fluorescent saliva droplets on Vectorchips were quantified by scanning the chips before and after the biting assays on Typhoon FLA 9000 gel scanner. Salivary droplet diameter was analyzed using ImageJ version 1.53c. The droplets were assumed to be deposited as hemispheres on the membrane surface, and the volume of droplets was estimated using this assumption.

The prepared TMD MLs on the nanogap were loaded onto a piezoelectric transducer (PZT, P-611.3X, Physik Instrumente) for XY scanning. To obtain a high-quality wavefront of the excitation beam, a He–Ne laser (594.5 nm, <1.0 mW) was coupled and passed through a single-mode fiber (core diameter of ~3.5 μm) and collimated again using an aspheric lens. Finally, the beam was focused onto the sample using a microscope objective (NA = 0.8, LMPLFLN100X, Olympus). The PL responses were collected using the same microscope objective (backscattering geometry) and passed through an edge filter (FEL0550, Thorlabs) to remove the fundamental laser line. The PL signals were then dispersed onto a spectrometer (f = 328 mm, Kymera 328i, Andor) and imaged using a thermoelectrically cooled charge-coupled device (CCD, iDus 420, Andor) to acquire the PL spectra. Before the experiment, the spectrometer was calibrated using a mercury–argon lamp. A 150 g/mm grating blazed to 800 nm (spectral resolution of 0.62 nm) was used for PL measurements. Time-resolved PL measurements were performed with a time-correlated single-photon counting (TCSPC) method. A commercially available TCSPC module (PicoHarp, PicoQuant GmbH) was used to obtain the PL decay curves. A 405 nm picosecond laser diode with an 80 MHz repetition rate was used as an excitation source.