Deuterated potassium dihydrogen phosphate (KD₂PO₄) or DKDP single crystals are widely used in non-linear optics as the second, third and fourth harmonic generators for Nd:YAG and Nd:YLF lasers. They are also found in electro-optical applications as Q-switches

Q-switching

Q-switching, sometimes known as giant pulse formation, is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high peak power, much higher than would be produced by the same laser if it were operating in a...

 for Nd:YAG, Nd:YLF, Alexandrite and Ti-sapphire laser

Ti-sapphire laser

Ti:sapphire lasers are tunable lasers which emit red and near-infrared light in the range from 650 to 1100 nanometers. These lasers are mainly used in scientific research because of their tunability and their ability to generate ultrashort pulses...

s, as well as for Pockels cells

Pockels effect

The Pockels effect , or Pockels electro-optic effect, produces birefringence in an optical medium induced by a constant or varying electric field. It is distinguished from the Kerr effect by the fact that the birefringence is proportional to the electric field, whereas in the Kerr effect it is...

.

DKDP is closely related to monopotassium phosphate

Monopotassium phosphate

Monopotassium phosphate -- 24 -- is a soluble salt which is used as a fertilizer, a food additive and a fungicide. It is a source of phosphorus and potassium. It is also a buffering agent...

 or KDP or KH₂PO₄. Replacement of hydrogen by deuterium

Deuterium

Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...

 in DKDP lowers the frequency of O-H vibrations and their overtones (high-order harmonics). Absorption of light by those overtones is detrimental for the infrared lasers, which DKDP and KDP crystals are used for. Consequently, despite higher cost, DKDP is more popular than KDP.

DKDP crystals are grown by a water-solution method at usual level of deuteration >98%.

See also

• Beta barium borate
  Beta Barium Borate
  Beta barium borate is a crystal frequently used for frequency mixing and other nonlinear optics applications...
  
   (BBO) - another popular non-linear crystal
• Lithium triborate
  Lithium triborate
  Lithium triborate LBO is a non-linear optics crystal. It has a wide transparency range, moderately high nonlinear coupling, high damage threshold and desirable chemical and mechanical properties. This crystal is often used for second harmonic generation of Nd:YAG lasers...
  
   (LBO) - another popular non-linear crystal
• Monopotassium phosphate
  Monopotassium phosphate
  Monopotassium phosphate -- 24 -- is a soluble salt which is used as a fertilizer, a food additive and a fungicide. It is a source of phosphorus and potassium. It is also a buffering agent...
  
   (KDP) - another popular non-linear crystal
• Non-linear optics
• Potassium titanyl phosphate
  Potassium titanyl phosphate
  Potassium titanyl phosphate or KTP is a nonlinear optical material which is commonly used for frequency doubling diode pumped solid-state lasers such as Nd:YAG and other neodymium-doped lasers. The material has a relatively high optical damage threshold , a great optical nonlinearity and excellent...
  
   (KTP) - another popular non-linear crystal
• Second harmonic generation
  Second harmonic generation
  An optical frequency multiplier is a nonlinear optical device, in which photons interacting with a nonlinear material are effectively "combined" to form new photons with greater energy, and thus higher frequency...
  
   (SHG)
• Third harmonic generation (THG)
• Two-photon absorption
  Two-photon absorption
  Two-photon absorption is the simultaneous absorption of two photons of identical or different frequencies in order to excite a molecule from one state to a higher energy electronic state. The energy difference between the involved lower and upper states of the molecule is equal to the sum of the...
  
   (TPA)
• Organic nonlinear optical materials
  Organic nonlinear optical materials
  Organic materials are expected to have relatively strong nonlinear optical properties due to delocalized electrons at \pi-\pi* orbitals. This expectation explains extensive search for better NLO materials among organic crystals.-L-arginine maleate dihydrate :...