Optical parametric sources Basics, implementation and applications

Lasers are increasingly used in many optical systems that exploit the properties of the coherent radiation emitted by these sources. However, despite numerous developments in wavelength-tunable lasers, their spectral coverage remains patchy, particularly in the infrared and when high peak power is required. One way of extending the spectral range covered by laser sources is to use non-linear optics processes to convert the frequency emitted by a laser to another frequency that is not directly accessible, while retaining various properties of the original laser emission, such as its pulse-time profile or spatial coherence.

Optical parametric sources are devices for efficiently generating such tunable coherent radiation from an incident laser beam. These sources are based on a quadratic non-linear optical process that converts an incident pump beam into two new tunable beams, called signal and complementary, the sum of whose pulses is equal to the pulsation of the pump beam. The radiation produced is therefore of longer wavelengths, making it possible to address the infrared directly from a technologically mature solid-state pump laser, generally emitting in the near infrared.

The aim of this article is to present an overview of optical parametric sources. Section 1 briefly describes the theoretical foundations and main operating principles of optical parametric sources (generators, amplifiers and optical parametric oscillators). Next, 2 describes the non-linear materials that are the key element of these sources. Then, their specific implementation is described for each of the operating time regimes: paragraph ...