Two photon absorption in silicon

In summary, the conversation discusses the two-photon absorption process and its existence in silica. It is mentioned that the two-photon absorption coefficient for silicon at 1500 nm is small and can only be observed with very high laser intensities. The source being used is a Tsunami-Opal femtosecond line, which has a relatively high peak intensity at 1500 nm. The conversation also mentions a study by Tsang et al. (2001) that provides a two-photon absorption coefficient of 0.45 cm/GW at 1540 nm for silicon.
  • #1
Barth
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0
How does work the two-photon absorption ?

Does it exist a Beer-Lambert law for this kind of process?
If yes, does someone know where i could find the order of magnitude of two-photons absorption coefficient for silicon at 1500 nm ?

Barth
 
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  • #2
Nonlinear absorption of this sort occurs for very high laser intensities, typically, for the infrared at least, one needs to blast silica with at least a nanojoule femtosecond pulse to observe these effects.

The two-photon absorption in silica at the kind of intensities you are likely to find from a 1500nm source, the TPA would be negligibly small.

Claude.
 
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  • #3
The source we are using is the "classic" Tsunami-Opal femtosecond line. We then have at 1500nm a relatively high peak intensity, that's why i would like to evaluate two-photon absorptions.
 
  • #4
2 photon absorption coeff in Si : 0.45 cm/GW at 1540 nm

Tsang et al, App Phys Lett, 80, 416 (2001)
 
  • #5
Thanks a lot
 
  • #6
Barth said:
The source we are using is the "classic" Tsunami-Opal femtosecond line. We then have at 1500nm a relatively high peak intensity, that's why i would like to evaluate two-photon absorptions.

Fair enough :blushing: . I never considered 1500 nm to be within your typical window of femtosecond pulse generation, but it appears I was wrong.

Claude.
 

FAQ: Two photon absorption in silicon

1. What is two photon absorption in silicon?

Two photon absorption in silicon is a process in which two photons of lower energy are absorbed simultaneously, resulting in the excitation of an electron to a higher energy state. This phenomenon occurs in materials with a bandgap smaller than the energy of a single photon, such as silicon.

2. How does two photon absorption occur in silicon?

In silicon, two photon absorption can occur when two photons with half the energy of the bandgap are absorbed simultaneously. The energy of these two photons combined is enough to excite an electron to a higher energy state.

3. What are the potential applications of two photon absorption in silicon?

Two photon absorption in silicon has potential applications in fields such as optical communications, biological imaging, and photovoltaics. It allows for the generation of light at shorter wavelengths, which could lead to faster and more efficient data transfer, higher resolution imaging, and more efficient solar cells.

4. How is two photon absorption in silicon studied?

Two photon absorption in silicon can be studied using techniques such as two photon absorption spectroscopy, which measures the absorption of two photons at different wavelengths. Other methods include nonlinear microscopy and pump-probe spectroscopy.

5. Are there any challenges associated with two photon absorption in silicon?

One challenge with two photon absorption in silicon is the low efficiency of the process. This means that a large number of photons is required to produce a significant effect, which can limit its practical applications. Another challenge is the need for high-intensity lasers to induce the two photon absorption, which can be expensive and difficult to control.

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