Measurement of wavelength using laser speckle
Light is a wave and it is well known waves can interfere creating patterns with constructive (bright) and destructive (dark) regions. For a laser this means we can create a granular pattern – a speckle pattern- that is rich in information about the incoming waves. We show how we can use this pattern from a laser as a signature to measure the laser wavelength to high accuracy and use it to remove laser fluctuations and thus stabilise a laser. This has applications for laser measurement, spectroscopy and stabilising lasers for quantum applications.