Definition of chirped mirrors

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Photonics Dictionary

chirped mirrors: Chirped mirrors are optical devices designed to manipulate the spectral properties of ultrashort laser pulses. They consist of multiple layers of dielectric coatings deposited on a substrate, where the thickness of each layer varies gradually across the mirror's surface.

The term chirped refers to the intentional variation of the thickness or refractive index of the layers along the mirror's surface, resulting in a chirped optical phase delay for different spectral components of the incident light. This chirped delay compensates for the dispersion introduced by optical elements in the laser system, such as lenses or prisms, allowing the pulses to be compressed or stretched in time.

Chirped mirrors are primarily used in ultrafast laser systems, where pulses with durations on the order of femtoseconds (10^-15 seconds) or picoseconds (10^-12 seconds) are generated. These ultrafast pulses are crucial for applications such as multiphoton microscopy, spectroscopy, material processing, and laser micromachining.

The main functions of chirped mirrors include:

Dispersion compensation: Chirped mirrors are designed to compensate for the dispersion introduced by other optical elements in the laser system, ensuring that the spectral components of the ultrashort pulses arrive at the focal plane simultaneously, resulting in minimal pulse broadening.

Pulse compression: By precisely tailoring the chirped delay across the mirror's surface, chirped mirrors can compress the duration of ultrashort laser pulses, allowing for higher peak powers and improved temporal resolution in applications requiring intense, short-duration pulses.

Pulse stretcher: In some laser systems, chirped mirrors are used as pulse stretchers to temporally elongate the ultrashort pulses before amplification, reducing the peak power and avoiding damage to optical components.

Chirped mirrors are essential components in the design of ultrafast laser systems, enabling precise control over pulse duration, temporal profile, and spectral characteristics, leading to advancements in various scientific and industrial applications requiring ultrashort laser pulses.