Sp 2300i

A 980-nm pulsed laser diode (1.6% duty cycle; 1 MHz period) was used to optically pump the fabricated topological cavities at room temperature. The light emitted from the cavities was collected by a 50× long-focal objective lens with a numerical aperture of 0.42 (M Plan Apo NIR B, Mitutoyo) and focused onto a spectrometer (SP 2300i, Princeton Instruments). The grating with 300 grooves mm⁻¹ blazed at 1.2 μm was used to spectrally disperse the PL emission from the cavities. The light was sent to either an IR array detector (PyLoN, Princeton Instruments) or an InGaAs IR camera (C10633, Hamamatsu) using a flip mirror in the spectrometer. For conventional mode imaging (not spectral imaging), a mirror was placed instead of the grating.

The measurements
were performed using a bespoke Raman system consisting of a monochromatic
laser (HeNe, ThorLabs) with a beam splitter and a long-pass filter
(RazorEdge, Semrock), an inverted optical microscope (IX71, Olympus),
a spectrograph (SP-2300i, Princeton Instruments), and a CCD camera
(iDus 401, Andor).^{55 (link),68 (link)−70 (link)} A 50×
objective was used to focus the laser (532 nm wavelength, 5 mW incident
power regulated by an attenuator) and collect the Raman and fluorescence
signals with an exposure time of 2 s in an accumulation mode (10 accumulations).
The CCD camera was calibrated over the spectral window using the Raman
spectrum of toluene. To take spatial variability into consideration,
an average signal from 10 different spots on the sample was reported.

PEF measurements were undertaken
using a bespoke Raman system that consisted of an inverted optical
microscope (IX71, Olympus), a monochromatic laser (green laser, ThorLabs)
with a beam splitter and long-pass filter (RazorEdge, Semrock), a
spectrograph (SP-2300i, Princeton Instruments), and a CCD camera (IXON,
Andor).^{12 (link),13 (link)} To focus the laser (532 nm wavelength, 5
mW incident power), a 50× objective was used. PEF spectra were
collected with an exposure time of 1 s. A 30 μL sample of the
analyte molecule TMPyP, RhB, or QDs with and without PMMA at a concentration
of 10^–9 M was deposited (drop-casting) above the
aligned FFNTs in the presence and absence of AgNPs. The average of
typically 10 measurements is reported. PEF measurements were performed
during an in situ applied electric field generated
through the application of 0–60 V, in steps of 5 V; the voltage
was applied using a PEW0028 DC power supply, following a process reported
previously.^{12 (link),35 (link)} Electrical cables or bonding
wire was used to connect the microfabricated chip using silver paint,
and then a DC voltage was applied during in situ Raman
measurements as shown in Figure 1a. Relaxation was also recorded after removing the
applied electric field or by applying low electric field values. The
current flow in the microfabricated chip was measured using a TENMA
digital multimeter (72-7725).