Våglängdslåsning

Våglängdslåsning, also known as wavelength locking, is a technique used in the field of optics to stabilize the frequency of a laser. This method is particularly important in applications where precise control over the laser's wavelength is crucial, such as in spectroscopy, interferometry, and laser cooling of atoms.

The principle behind våglängdslåsning involves using a reference cavity to compare the laser's output with a stable reference wavelength. The reference cavity is typically a high-finesse optical cavity that resonates at a specific wavelength. The laser light is injected into this cavity, and any deviation from the reference wavelength causes a phase shift in the reflected light.

This phase shift is detected using a photodetector, which converts the optical signal into an electrical signal. The electrical signal is then processed by a feedback system, which adjusts the laser's frequency to minimize the phase shift. This feedback loop ensures that the laser's wavelength remains stable and locked to the reference wavelength.

Våglängdslåsning can be implemented using various types of reference cavities, including Fabry-Perot cavities and etalons. The choice of cavity depends on the specific requirements of the application, such as the desired wavelength range and the required stability.

One of the key advantages of våglängdslåsning is its ability to achieve high stability and precision. By locking the laser to a reference wavelength, the technique can reduce the laser's linewidth to a fraction of a hertz, making it suitable for high-precision measurements.

In summary, våglängdslåsning is a powerful technique for stabilizing the frequency of a laser, enabling precise control over the laser's wavelength. Its applications range from fundamental research to practical technologies, making it an essential tool in the field of optics.