Ateneo KISLAP

Resonance and Resonators

A briefer on resonance and resonators

What is resonance?

In physics, resonance is a phenomenon that occurs due to constructive interference. It happens when the frequency of an applied force is equal to the natural frequency of the system on which it acts. This causes an increase in vibration amplitude of the object and leads to energy build-up.

What are resonators?

Resonators use the concept of resonance for many applications. That is, it oscillates with larger amplitudes at certain frequencies than at other frequencies. Resonators can be used in generating waves with specific frequencies or selecting certain frequencies from a wave signal. The oscillation within a resonator can either be mechanical or electromagnetic. This device is commonly present in many sub-disciplines of science as mechanical, acoustic, optical, cavity, and microwave resonators. With this, resonators are used in photonic and optical devices, particle accelerators, cars, musical instruments, electronics, and other various technologies.

The Fabry-Perot Interferometer

An example of which is an optical resonator like a Fabry-Pérot interferometer. A classic Fabry-Pérot interferometer is designed by two partially reflecting mirrors.

Figure 1. Fabry-Pérot interferometer

Each time the light interacts with one of the surfaces, a fraction of it is transmitted out and the remaining portion is reflected back. The net effect of such a phenomenon would be to break a single beam into multiple beams which can interfere (combine) with each other. At resonant frequency, the reflections constructively interfere or add together so that the field amplitude in the resonator reaches its maximum value.

References

[1] C. Chung-Ping, T. Pi-Cheng, S. Lih-Horng, W. Yung-Cheng and E. Manske. “Fabry–Perot displacement interferometer for the measuring range up to 100 mm.” Measurement, vol. 46, no. 10, pp. 4094-99, 2013.

[2] H. D. Young and R. A. Freedman, Sears and Zemansky’s University Physics, volume 1, 15th ed. Singapore: Pearson Education Limited, 2020.

[3] L. Critchley, “Recent Advances in Resonator Technologies.” AZoNano. https://www.azonano.com/article.aspx?ArticleID=4652 (accessed May 21, 2022).

[4] J. Liu, Principles of Photonics, LA, USA: Cambridge University Press, 2016. [Online]. Available:https://www.cambridge.org/core/books/abs/principles-of-photonics/optical-resonance/A5D35FE42522BC75139EFA5781DF1FE8. Accessed: May 21, 2022.