GEMINI an ultra-stable interferometer
GEMINI is a novel and compact interferometer that can guarantee very high robustness
and stability between the two generated replicas of light.
The exceptional performances of this device can be exploited in many different
applications, such as time- and frequency-resolved fluorescence, coherent Raman,pump-probe, two-dimensional spectroscopy and studies on single molecules.

Key Features• High throughput that allows high sensitivities• ≈1 attosecond stability between the two replicas of light• Scan range selectable by the user• Compact and low-cost• Insensitive to vibrations

Applications• Interferometry• Generation of pulse pairs
GEMINI IN DETECTION PATH
• Time- and frequency- resolvedfluorescence• Pump-probe spectroscopy• Coherent Raman spectroscopy
GEMINI IN EXCITATION PATH
• Fluorescence Excitation-Emission Maps
• Characterization of single molecules

SampleTime- and frequency-resolved fluorescence with a single
TCSPC detector
Experimental setup: GEMINI interferometer is placed incollection before the detector (a SPAD or PMT) connected
to a TCSPC. This allows one to resolve the fluorescencewavelength axis while preserving the temporal resolution.

SPAD orPMTGEMINI

Interferometer

TCSPC

The GEMINI canbe placed as aturn-key add-on
deviceNarrowband
pulsed excitation

8000.9Rhodamine B + Nile Red

10.8

700
650600Intensity (a.u.)

0.7
Intensity (a.u.)

Wavelength (nm)

750

0.1

0.5
0.4
0.3
0.2

550
500

t=4.2 ns0.6

t=1.8 ns0.1-1 012

3 4 5Time (ns)

768

0.01

9-1 0123 4 5 6Time (ns)7809

Semi-log plots of fluorescence decay
traces at ≈575 nm (green curve) and ≈675
nm (purple curve).

Fluorescence maps as a function ofdetection wavelength and emission time fora mixture of Rhodamine B and Nile Red in
acetone solution.

540580 620 660 700
Wavelength (nm)740

Integrated
spectraofthetwofluorophores computed from thecorrespondent Decay Associated Spectra(DAS) and lifetimes.

1(c)Intensity(a.u.)

0.9

0.8

0.7

0.6

Intensity(a.u.)

0.5

0.4

0.3

0.2

800

0.1

01

2

34

5678

LHCS3R complex

750

0007

700

(a)

9.0

8.0

7.0

9(a) Fluorescence map of the LHCSR3 complex from C.
reinhardtii; (b-c) Marginals of (a), obtained by integrating the map along the horizontal and vertical directions,
respectively, showing the overall fluorescence spectrum
and decay dynamics.
A. Perri et al., Opt. Express 26, 2270-2279 (2018).

18

6.0

7

5.0

6

4.0

3 4 5
Time (ns)

3.0

2

2.0

1

1.0

-1 0(b)0056

650

GEMINI + single PMT
detectorStandard grating-based
spectrometer

9057

Wavelength (nm)

-1008

0500

0550
550600 650 700
Wavelength (nm)
600

650

700

750750550600 650 700Wavelength (nm)750

Comparison of fluorescence emission spectra of Rhodamine B, measured inthe same experimental conditions. Excitation laser: =530 nm, P=1 W.

Coherent Raman (Stimulated Raman Scattering - SRS)and Pump-Probe Spectroscopy
SampleBroadband
Probe/Stokes

GEMINI

PhotodiodeInterferometer

platedModu band Pumw
Narro

Wavelength (nm)

1400

1400

Lock-in
Amplifier(a)Experimental setup: GEMINI interferometer isplaced in the probe/Stokes beam after thesample, allowing one to measure SRS orpump-probe spectra up to MHz modulation
frequencies.

(b)

1300
1200
1100

5-5(c)(a) Two-dimensional ΔT⁄T(λ,τ) map for a graphite sample prepared byliquid phase exfoliation. (b) ΔT⁄T spectra at selected probe delays; (c) ΔT⁄T dynamics at 1270-nm probe wavelength (red circles) together witha bi-exponential fit (black solid line). Inset: zoom of the signal for
negative delays.

Chemometric analysis of the acquired dataset. (a) SRS spectra for
PMMA (solid black line) and PS (dotted red line). (b) False-color imageof the sample, showing a central bead of PMMA (in red), surroundedby smaller beads of PS (in green). (c) and (d): concentrations maps ofPMMA and PS.
F. Preda et al., Opt. Lett. 41, 2970-2973 (2016).
J. Réhault et al., Opt. Express 23, 25235-25246 (2015).

Comparison with Monochromators
The GEMINI is designed to be added to your setup to extract the spectrum of any light source, coherent or not.
It can replace monochromators, since it overcomes their main drawbacks in terms of low throughput, fixed spectral
resolution and limited spectral coverage

atormorochExcitation
Laser

GEMINI

Interferometer

Fluorescent
SampleMonochromator

PMTdetector

MonPMTdetector

GEMINICOMPARISON between GEMINI and a monochromator. The fluorescence of a sample is collected at 90° and measured
with PMT detectors. The GEMINI and the monochromator enable to spectrally resolve the fluorescence. With the GEMINI,
one can obtain the same S/N obtained with a monochromator with ~100 times lower excitation light power.

Excitation-Emission Maps (EEMs) of Single Molecules
The GEMINI can be placed as aturn-key add-on device
SampleShort PassFilter
WhiteLightSource

Broadband
excitation

Objective
Beam Splitter

GEMINI

InterferometerLong Pass Filter

Spectrograph

Flip Mirror
Photodiode andTCSPCEXCITATION-EMISSION MAP

Single molecule: Terrylene diimide derivative

TIME and FREQUENCY-RESOLVED MAP

FT0A

B

GEMINI in Excitation
Photodiode+TCSPC in Detection
Decay Time [ns]Detection Wavenumber /103 [cm-1]

Detection Wavenumber /103 [cm-1](from Spectrograph)

GEMINI interferometerallows the characterizationof single molecules withlow acquisition times andexceptional accuracy andsensitivity

GEMINI in Excitation
Spectrograph in DetectionGEMINI Interferometer Position [mm]C

Excitation Wavenumber /103 [cm-1]

Excitation Wavenumber /103 [cm-1]

Thyrhaug et al., “Single-molecule excitation–emission spectroscopy”, PNAS 201808290 (2019).

Single Molecule interferogram (A) and relative Excitation-Emission Map (B) obtained via Fourier Transform (FT) along the x-axis.
(C) Excitation-energy versus emission-intensity decay for a single molecule constructed from an interferometric TCSPC experiment.

Technical Specifications
50VERSION
Spectral range [nm]SL

400 - 2300 (Standard)
250 - 3500 (Ultra-broadband)
500 - 4200 (On request)

Max. Delay τ [fs @ λ=600 nm]-100 → 700-100 → 2000

Delay τ Stability< 1 a�osecond

Dimensions [mm]176 x 44 x 54.5

Weight [kg]Spectral Resolution

403020100.4

Specifications can be subject to change without notice.
For more information, please contact us via e-mail at info@nireos.com or visit our website www.nireos.com