Preda said. ‘Back then, it was a natural first step for us to start by working in the world of academia.’

Gemini is now used in a

wealth of scientific research applications, including measuring static or time- resolved fluorescence spectra, for broadband pump-probe or coherent Raman spectroscopy, and quantum optics. Nireos is also expanding into

the industrial market, recently introducing a hyperspectral camera, Hera, to its product range, and with plans to launch an ultra-broadband spectrometer, Spectre. Preda explained: ‘As we continue to focus on the world of academia, these new products also open up our expertise to industrial applications, such as quality control, for example.’ One common research

application, time and frequency resolved fluorescence, highlights how Gemini can be used and why it’s different from other devices on the market. In this application, the Gemini interferometer is placed between the sample and

detector, which is usually a Spad or photomultiplier tube. The Gemini is factory-calibrated and aligned for turn-key integration in any existing setup. So, the user doesn’t have to worry about any complicated optical alignment procedures. A pulsed laser then excites the

fluorescent sample. The signal is sent through the Gemini interferometer and measured by the Spad, which is connected to a time-correlated single photon counting (TCSPC) system. While Gemini provides the spectral resolution, the TCSPC provides the temporal resolution. Using this technique, 2D maps

of the sample’s fluorescence are produced as a function of the emission wavelength and decay time, with high temporal and spectral resolution. This is just one example of how Gemini can be incorporated and used in an existing optical setup. In its latest white paper,

Nireos reveals how the Gemini provides an innovative approach also to broadband pump-probe spectroscopy, using a single- pixel detector and single channel

“As we focus on academia, these new products open our expertise to industrial applications such as quality control”

lock-in amplifier. ‘Pump-probe signals are typically very small and lie on a large background, so they require modulation transfer techniques, which consist of modulating the pump beam and synchronously demodulating the probe to detect the pump-induced transmission changes,’ Preda explained. ‘In the kHz regime, parallel

detection systems based on dispersive techniques are straightforward to implement, as these devices are capable of single-shot detection at these frequencies.’ However, as the sensitivity of pump-probe depends on the repetition rate of the system, the desire would be to exploit the higher repetition rates of MHz lasers. In this range, no

dispersive devices capable of single-shot detection exist, so the serial approach is typically used measuring pump-probe signals at individual probe wavelengths, selected by an interference filter or a monochromator. A parallel approach would be

preferable, as it greatly reduces the measurement time, and it minimises distortions in the retrieved spectra that could arise from slow drifts in the pump power, gradual sample damage or gradual misalignment of the detection chain or the spatial overlap of the two pulses. ‘With Gemini, we introduce

a new and highly-versatile approach to broadband pump-probe spectroscopy, as it combines broad spectral coverage, parallel acquisition, and high sensitivity,’ Preda said. ‘It can be used in almost all the spectroscopy experiments out there, whether that’s linear spectroscopy such as fluorescence, but also in non- linear spectroscopy, such as pump-probe or coherent Raman experiments.’ EO

New White Paper now online


Nireos reveals how the Gemini interferometer provides an innovative approach to broadband pump-probe spectroscopy, using a single-pixel detector and single channel lock-in amplifier.

Read more in the white paper online

Electro Optics

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