Determination of the coherence length and beat frequency length using a p-emf sensor
DOI:
https://doi.org/10.31349/RevMexFisE.22.020220Keywords:
temporal coherence, coherence length, p-emf sensors, interferometryAbstract
The coherence of light is essential for understanding interference phenomena, which are pivotal in a wide range of applications. However, due to the technical challenges of conventional methods, quantifying coherence is difficult to achieve in undergraduate optics laboratories. In this work, we present a modification of a method and experimental setup that can enhance the understanding of coherence concepts employing a sensor based on the non-steady-state photo-electromotive force (p-emf) effect. This p-emf sensor generates an electrical current proportional to the square of the interference pattern’s visibility, eliminating the need for image processing and high-quality optical elements, and allowing for real-time measurements. We demonstrated the method by measuring the coherence length of a He-Ne laser and the corresponding length associated with the beat frequency of the laser cavity’s longitudinal modes. This approach is robust, straightforward and simple, making it suitable for implementation in undergraduate optics laboratories.
References
L.-P. Leppänen et al., Measurement of the degree of temporal coherence of unpolarized light beams, Photonics Res. 5 (2017) 156, https://doi.org/10.1364/PRJ.5.000156
R. Dubey and R. Kumar, A simple setup for measurement of the coherence length of a laser diode using holographic optics, Eur. J. Phys. 40 (2019) 055304, https://doi.org/10.1088/1361-6404/ab1d6a
P. Pogany et al., Measuring the coherence function of continuous-wave lasers by a photorefractive grating method, Appl. Opt. 38 (1999) 516, https://doi.org/10.1364/AO.38.000516
S. Alaruri, Experimental Method for Determining the Coherence Length of CW Lasers Using a Michelson Interferometer, J. Laser Appl. 5 (1993) 33, https://doi.org/10.2351/1.4745328
M. Illarramendi et al., Adaption of the Michelson interferometer for a better understanding of the temporal coherence in lasers, In X. Liu and X.-C. Zhang, eds., 14th Conference on Education and Training in Optics and Photonics: ETOP 2017, vol. 10452, International Society for Optics and Photonics (SPIE, 2017) p. 1045249, https://doi.org/10.1117/12.2266546
S. Stepanov, Chapter 6 - Photo-electromotive-force effect in semiconductors, In H. Singh Nalwa, ed., Handbook of Advanced Electronic and Photonic Materials and Devices, pp. 205-272 (Academic Press, Burlington, 2001), https://doi.org/10.1016/B978-012513745-4/50026-3
E. Hecht, Optics 5th ed. (Pearson Education India, 2017), p. 601 and p. 628
P. Rodriguez-Montero, C. M. Gomez-Sarabia, and J. Ojeda-Castañeda, Adaptive photodetector for assisted Talbot effect, Appl. Opt. 47 (2008) 3778, https://doi.org/10.1364/AO.47.003778
P. R. Montero, Observation and verification of the Fresnel and Arago interference laws using adaptive photodetectors, Rev. Mex. Fis. E 18 (2021) 44, https://doi.org/10.31349/RevMexFisE.18.44
S. Stepanov et al., Effective broadband detection of nanometer laser-induced ultrasonic surface displacements by CdTe: V adaptive photoelectromotive force detector, Appl. Phys. Lett. 84 (2004) 446, https://doi.org/10.1063/1.1640466
M. A. Carrasco, P. R. Montero, and S. Stepanov, Measurement of the coherence length of diffusely scattered laser beams with adaptive photodetectors, Opt. Commun. 157 (1998) 105, https://doi.org/10.1016/S0030-4018(98)00537-9
Y. Ding et al., Electric-field correlation of femtosecond pulses by use of a photoelectromotive-force detector, JOSA B 15 (1998) 2013, https://doi.org/10.1364/JOSAB.15.002013
C.-C. Wang et al., Human life signs detection using high-sensitivity pulsed laser vibrometer, IEEE Sens. J. 7 (2007) 1370, https://doi.org/10.1109/JSEN.2007.905041
Y. Pan et al., Low-coherence optical tomography in turbid tissue: theoretical analysis, Appl. Opt. 34 (1995) 6564, https://doi.org/10.1364/AO.34.006564
B. E. Saleh and M. C. Teich, Fundamentals of photonics (John Wiley & Sons, Ltd, 1991), p. 532, https://doi.org/10.1002/0471213748.fmatterindsub
E. F. Erickson and R. M. Brown, Calculation of fringe visibility in a laser-illuminated interferometer, JOSA 57 (1967) 367, https://doi.org/10.1364/JOSA.57.000367
M. K. Singh and S. Datta, Dual measurements of temporal and spatial coherence of light in a single experimental setup using a modified Michelson interferometer, Rev. Sci. Instrum. 92 (2021) 105109, https://doi.org/10.1063/5.0041438
K. Pieper et al., Visualizing and manipulating the spatial and temporal coherence of light with an adjustable light source in an undergraduate experiment, Eur. J. Phys. 40 (2019) 055302, https://doi.org/10.1088/1361-6404/ab3035
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2025 P. Rodríguez-Montero, A. S. Cruz-Félix, E. Tepichin-Rodríguez, A. F. Muñoz-Potosi, L. G. Valdivieso-González

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Authors retain copyright and grant the Revista Mexicana de Física E right of first publication with the work simultaneously licensed under a CC BY-NC-ND 4.0 that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.