Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Nonlinear frequency conversion: sum frequency generation

Description

This lecture covers the concept of nonlinear frequency conversion, focusing on sum frequency generation (SFG) and second harmonic generation (SHG). It explains the principles behind these processes, the importance of phase matching, and the use of birefringent crystals for efficient frequency conversion. The instructor discusses the theory and modern applications of lasers in generating new wavelengths through nonlinear processes.

This video is available exclusively on Mediaspace for a restricted audience. Please log in to MediaSpace to access it if you have the necessary permissions.

Watch on Mediaspace

Official source

Related concepts (32)

Second-harmonic generation

Second-harmonic generation (SHG, also called frequency doubling) is a nonlinear optical process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons (equivalently, twice the frequency and half the wavelength), that conserves the coherence of the excitation. It is a special case of sum-frequency generation (2 photons), and more generally of harmonic generation.

Nonlinear optics

Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear.

Frequency mixer

In electronics, a mixer, or frequency mixer, is an electrical circuit that creates new frequencies from two signals applied to it. In its most common application, two signals are applied to a mixer, and it produces new signals at the sum and difference of the original frequencies. Other frequency components may also be produced in a practical frequency mixer. Mixers are widely used to shift signals from one frequency range to another, a process known as heterodyning, for convenience in transmission or further signal processing.

Laser diode

A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. Driven by voltage, the doped p–n-transition allows for recombination of an electron with a hole. Due to the drop of the electron from a higher energy level to a lower one, radiation, in the form of an emitted photon is generated. This is spontaneous emission.

Birefringence

Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress.

Related lectures (32)

Frequency conversion: non-linear optics

Explores the concept and theory of frequency conversion in non-linear optics, emphasizing the importance of phase matching for efficient conversion.

Nonlinear Optics III: Light-Matter Interaction

Covers pulsed optics, coherent spectroscopy, and nonlinear optical effects.

Nonlinear Optics: Light-Matter Interaction

Explores nonlinear optics, covering light-matter interaction, second and third order effects, phase modulation, and frequency conversion processes.

Nonlinear Optics: Optical Kerr Effect and Phase Conjugation

Explores nonlinear optics phenomena, including optical rectification, frequency conversion, and phase conjugation.

Doppler Broadened Absorption: Resonators, 3 Level System