Question about SPDC (Making entangled photons)

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SUMMARY

The discussion centers on the process of spontaneous parametric down conversion (SPDC) for generating entangled photons using a beta-barium borate (BBO) nonlinear crystal. It is established that while BBO crystals can operate over a broad range of wavelengths, the specific wavelength for photon generation is determined by the laser used and the configuration of the crystal. For instance, to produce two photons at 800 nm, a 400 nm laser must be utilized, and the BBO crystal must be appropriately cut for the desired wavelength. This highlights the importance of matching the laser wavelength with the crystal's specifications.

PREREQUISITES
  • Understanding of spontaneous parametric down conversion (SPDC)
  • Knowledge of beta-barium borate (BBO) nonlinear crystals
  • Familiarity with laser wavelength selection and its impact on photon generation
  • Basic principles of entangled photon production
NEXT STEPS
  • Research the properties and applications of beta-barium borate (BBO) crystals in photonics
  • Learn about laser selection criteria for SPDC processes
  • Explore the theory behind entangled photon generation and its implications in quantum optics
  • Investigate the effects of crystal cutting on wavelength specificity in SPDC setups
USEFUL FOR

Researchers in quantum optics, experimental physicists, and anyone involved in the development of entangled photon sources will benefit from this discussion.

Xyius
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Hello everyone,

I have a question about the process of spontaneous parametric down conversion (or SPDC). This process is used to create two entangled photons in the visible regime by shining a laser through a beta-barium borate (BBO) nonlinear crystal.

My question is, can this process be done at ANY wavelength in the visible regime? Or is the wavelength specific to the crystal?

So for example, say I wanted two photons at 800 nm. Does this mean I should choose a 400 nm laser to shine through the crystal so it splits into two 800 nm photons? Do I have the choice of wavelength (within the boundaries of the visible regime)?
 
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Your setup will be for a specific laser line; the BBO crystal needs to be cut for your wavelength, and ditto for wave plates.

But the BBO crystals can function over a broad range.
 

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