The birth of SPDC photons
  • February 21, 2024
  • Noa Bloch
  • 0

The birth of SPDC photons

In nonlinear crystals, a special nonlinear process occurs. A pump photon is spontaneously converted into two complementary photons with lower energy. In this process both energy and momentum are conserved, i.e .,  ωps + ωi  and kp =ks + ki

In PPKTP or APKTP Crystals the momentum mismatch of the process is compensated by the crystal reciprocal vector which is determined by the spatial frequency  kp = ki +ks + kG

Vacuum energy fluctuations give rise to the spontaneous creation of many random photons.  However, the output photons of the SPDC (spontaneous parametric down-conversion nonlinear process) are the ones that conserve momentum and energy.

Spdc photons Raicol Quantum
Momentum conservation law

In type 1 SPDC, all the photon pairs that conserve momentum are positioned on a ring-shaped structure:

Changing the temperature of the crystal or wavelength of the pump will change the phase-matching condition thus, the radius of the rings will be changed as well, as seen in the movie.

Let's Talk


Phone: +972-3-7294472
Address: Hamelacha 22,
Rosh Ha’Ayin 4809162, Israel

Finding Something Interesting ?

    Interested in: