Use gas laser for gas detection

Learn the entire process from gas-filled fiber Raman laser generation to its application on photoacoustic detection of CO2.

Gas laser

Hvad går øvelsen ud på?

The target of the experiment is to help the student briefly learn the entire process from gas-filled fiber Raman laser generation to its application on photoacoustic detection of CO2.

  1. Learn the basic concepts of Raman lasing, anti-resonant hollow-core fiber, and photoacoustic detection.
  2. Learn the experimental generation process of gas-filled fiber Raman laser.
  3. Learn the characterization methods of Raman laser
  4. Learn dilution of CO2 in Ar with mass flow controllers.
  5. Learn the photoacoustic detection and data process procedures.

Hvordan foregår øvelsen?

The exercise is conducted in the facilities of DTU Electro.

In particular, the student will use the gas-filled hollow-core fiber lasers in the GasLab, photoacoustic chambers and cells, as well as optical microscopes. 

Hvilke faciliteter kommer du til at bruge?

DTU Electro, GasLab. The lab consists of:

  • Different high pulse energy lasers in the near-infrared and mid-infrared spectral region
  • Ultrafast oscilloscope
  • Various optical spectrometers
  • Photoacoustic microscope
  • Various mass flow controllers
  • Photoacoustic gas chamber
Tilmeldingen til SRP-øvelser 2023 er lukket

The student will be able to integrate the obtained data with existing literature for a broader research on environmental sensors, its advantages and challenges and the identify the limitation of current commercial solutions.

Environment: Air quality, need for pollution monitoring systems.

  1. Brief introduction of the entire chain of the experiment, i.e., pump laser preparation, Raman laser generation, CO2 sample preparation, photoacoustic detection, and data process.
  2. Explanation of the basic principle and performance of CO2-filled fiber Raman laser. This part will first introduce the basic principle of anti-resonant hollow-core fiber technology. Then a scanning electron microscope (SEM) of the fiber used in the experiment will present, to show the real fiber profile and key parameters. Afterwards, the principle of stimulated Raman scattering will be explained, and a simple formula will be presented to show how calculate the Raman laser wavelength according to a known pump wavelength in the case of CO2 gas.
  3. Visit the experimental setup of the fiber Raman laser and test the Raman laser performance, including how to efficiently coupling pump laser into the anti-resonant hollow core fiber, how to control the gas pressure inside the anti-resonant hollow core fiber, how to measure optical spectrum, pulse profile, and pulse energy of the Raman laser, etc.
  4. Explanation of the principle and process of photoacoustic detection, e.g., the configuration of the acoustic chamber, data acquirement process, gas sample preparation with mass flow controllers, etc.
  5. Visit the photoacoustic experiment setup, and explain the relevant devices (e.g., mass flow controller, acoustic chamber, microphone, lock-in amplifier, etc.).
  6. Couple the collimated Raman laser into photoacoustic resonant cell, and perform the CO2 detection experiment. In this part, you will see how to dilute the CO2 to a specified concentration, how to capture photoacoustic signal with a microphone, how does the photoacoustic signal response to difference CO2 concertation, how to process the data, etc.
  • Measured spectra of the gas-filled hollow core fiber lasers
  • Microscope optical images
  • Acoustic signals and photoacoustic recordings
  • Data on the performance of the sensor

Forslag til litteratur, du kan bruge i din opgave og som baggrund for øvelsen:

  • Wang, Yazhou, et al. "High pulse energy and quantum efficiency mid-infrared gas Raman fiber laser targeting CO2 absorption at 4.2 µm," Opt. Lett. 45, 1938-1941 (2020)
  • Wang, Y., Feng, Y., Adamu, A.I. et al. ”Mid-infrared photoacoustic gas monitoring driven by a gas-filled hollow-core fiber laser.” Sci Rep 11, 3512 (2021).

NB: Når du har tilmeldt dig, vil du få besked, hvis der er litteratur, du skal læse som forberedelse til øvelsen.

  • Fysik: Light propagation in optical fibers and guiding properties of light. Acoustic technology.
  • Optica fibers
  • Raman lasers
  • Photoacoustic detection

Tidspunkt og varighed

The exercise has 2 days duration:

  • 21 .februar kl. 10 - 14
  • 22. februar kl. 10 -14

Antal deltagere

5

Opfølgende møde

- hvor du kan du få hjælp til  din databehandling og stille spørgsmål:

  • 7. marts kl. 14-15

Sprog

Engelsk

Arrangør og adresse

DTU Electro
Lyngby Campus

Kontakt

Kyv Kyvsgaard

Kyv Kyvsgaard Kommunikation og Outreach Institut for Elektroteknologi og Fotonik