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Ultrafast spectroscopy with ultrashort pulses of light

Debanuj Chatterjee, Eve-Line Bancel, Simon Boivinet, Siddharth Sivankutty, Hérve Rigneault, Pascal Szriftgeiser, Steven Cundiff and Arnaud Mussot

(D.C. : postdoc @ PhLAM, University of Lille, France)

​

Roots@IISER Kolkata, India

Funded by the

European Union

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Ultrafast spectroscopy with ultrashort pulses of light

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Spectroscopy : Principle

(Nathalie Picqué et al, Nature Photonics, 2019)

Dual comb spectroscopy

But why dual comb spectroscopy?

Optical frequency comb

• Equally spaced frequencies
• Ruler of light
• Pulse train in time domain

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Ultrafast spectroscopy with ultrashort pulses of light

Grating based optical spectrum analyzer

PD

movement

Source

Tunable band pass filter

It is very slow! (~seconds)

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Fourier Transform Infrared Spectroscopy : Principle

(Scott Diddams et al, Science, 2020)

Mechanical control

It is slow (~milliseconds)

Frequency domain

Time domain

Downconversion

Easy

detection!

Michelson interferometer

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Dual Comb Spectroscopy : Principle

Time domain

(Takuro Ideguchi, Optics & Photonics News, 2017)

Frequency domain

Vernier effect

f₁

f₂=f₁+Δf

Δf

f_AOM

1/f₁

1/f₂

Optical

RF

Dual comb spectroscopy have no moving parts

It is fast (~100 microseconds)

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Speed Improvement Strategy

Unused space

(Yu Zhang et al, Optics Letters, 2021)

Strategy : Increase Δf

(to pack more ifg pulses)

1/Δf

Time domain interferogram

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Speed Improvement Strategy

Strategy : Increase Δf

1/Δf

Time domain interferogram

But, there is a problem…

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Problem of RF Spectral Aliasing

RF frequency

Power

RF frequency

Power

Δf increase

Δf

Spectral aliasing

Frequency domain ifg

Time domain ifg

Voltage

Time

Δf increase

Time

Voltage

Fundamental

comb

High-order

comb

Low Δf

High Δf

1/Δf

1/Δf

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Speed Improvement Strategy

Strategy : Time domain shaping of optical pulses (time multiplexing) exploiting the agility provided by EOM combs

Time domain interferogram

Extra peak generated

Time

In the frequency domain : Increase in SNR

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Ultrafast spectroscopy with ultrashort pulses of light

(~microseconds)

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Experimental Scheme

AWG : arbitrary waveform generator, AOM : acousto optic modulator, EDFA : Erbium doped fiber amplifier, DCF : dual core fiber (nonlinear), IM : intensity modulator, PD : phorodetector, WS : waveshaper, VOA : variable optical attenuator

• Multiplexed case provides a larger SNR (for same acquisition time)
• Multiplexed case provides a faster acquisition (for same SNR)

Cross section of DCF

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Shorter acquisition time for same SNR

• Multiplexed case provides a shorter acquisition time for the same SNR compared to the standard case
• For M=3.3, there is about 12 times gain in recording time with multiplexing

Same SNR

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Ultrafast spectroscopy with ultrashort pulses of light

(pulse duration ~100 picoseconds)

Arbitrary waveform generator

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Ultrafast spectroscopy with ultrashort pulses of light

(pulse duration ~100 femtoseconds)

Results from Simon Boivinet, 2024

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Ultrafast spectroscopy with ultrashort pulses of light

multidimensional

Work in progress…

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Perspectives

Multidimensional spectroscopy with multicore fibers

Compressive sensing : hybrid approach

Fast sensing in engines

(Eve-Line Bancel et al, Nature Communications, 2023)

(Anthony Draper et al, Optics Express, 2019)

(Akira Kawai et al, Scientific Reports, 2021)

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Acknowledgements

Nonlinear optics group at PhLAM

Matteo Conforti

(faculty)

Arnaud Mussot

(group leader)

Francesco Tani

(faculty)

Siddharth Sivankutty

(faculty)

Thomas Bunel

(PhD student)

Eve-line Bancel

(PhD student)

Simon Boivinet

(Postdoc)

Debanuj Chatterjee

(Postdoc)

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Thank You!