Dispersion Compensating Etalons
Etalons, when used in reflection (all-pass) mode, have a series of group delay peaks with a periodic frequency spacing and are typically used in telecom for dispersion compensation applications. Etalons are characterized by their Free Spectral Range (FSR) - the frequency spacing between peaks - and their Finesse - which essentially governs the shape of the transmission peaks.
All-pass etalon filters typically consist of a single spacer layer with a high reflector on one side and a partial reflector on the other side. As with regular etalons, for FSR values below 1000 GHz, the spacer is usually fabricated from a substrate material with a substrate parallelism better than 1-5 arc-seconds.
For large thermal tuning, Si substrate materials can be used in dispersion compensation etalons and they can be designed for a wide range of FSR and peak group delay values.
Please contact us with your all-pass etalon requirements.