Stress compensating anti-reflection coating
Example: double-sided optical element for the multiterawatt few-cycle light wave synthesizer based on optical parametric amplification.
Front side: dispersive mirror working in the spectral range from 560 to 1030 nm with average value of the GDD of +75 fs2. Due to mechanical stresses of mirror's layers the substrate become bended, that distorts wave front quality resulting in the distorting of the beam waveform of laser system.
Back side: To compensate this stress, the substrate back side can be covered with an anti-reflection coating having approximately the same mechanical stress. This anti-reflection coating will also suppress the unwanted reflection from the back side.
Suitable anti-reflection coating has been obtained with the help of Gradual Evolution and Thin Layer Removal procedure of OptiLayer Software. Necessary preliminary estimations have been done with the help of our AR calculator.
|Comparison of main parameters of the dispersive mirror and anti-reflection coating:|
|Parameter||Dispersive Mirror||Anti-reflection Design|
|Number of layers:||74||71|
|Total physical thickness||7568 nm||7417 nm|
|Total optical thickness @ 800 nm||13435 nm||13327 nm|
|Physical thickness of all Nb2O5 layers||2979 nm||3077 nm|
|Physical thickness of all SiO2 layers||4589 nm||4340 nm|
Learn more in our publication:
T. Amotchkina, M.Trubetskov, Y. Pervak, L. Veisz, V. Pervak, Stress compensation with antireflection coatings for ultrafast laser applications: from theory to practice, Optics Express, Vol. 22, pp. 30387-30393 (2014)