Study on Frequency Coherence Properties of Light Beams
| Autor: | Shuo Fu Chen, Liang Xie, Ninghua Zhu, Yu Liu, Ji Min Wen, Wei Li, Hai Qing Yan, Yali Zhang, Jian Hong Ke, Xin Wang, Lixian Wang |
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| Rok vydání: | 2009 |
| Předmět: |
Physics
Coherence time business.industry Physics::Optics Condensed Matter Physics Laser Atomic and Molecular Physics and Optics law.invention Laser linewidth Optics law Frequency domain Spectral width Electrical and Electronic Engineering business Intensity modulation Frequency modulation Coherence (physics) |
| Zdroj: | IEEE Journal of Quantum Electronics. 45:514-522 |
| ISSN: | 0018-9197 |
| DOI: | 10.1109/jqe.2009.2013102 |
| Popis: | This paper presents a new concept of frequency coherence in the frequency-time domain to describe the field correlations between two lightwaves with different frequencies. The coherence properties of the modulated beams from lightwave sources with different spectral widths and the modes of Fabry-Perot (FP) laser are investigated. It is shown that the lightwave and its corresponding sidebands produced by the optical intensity modulation are perfectly coherent. The measured linewidth of the beat signal is narrow and almost identical no matter how wide the spectral width of the beam is. The frequency spacing of the adjacent FP modes is beyond the operation frequency range of the measurement instruments. In our experiment, optical heterodyne technique is used to investigate the frequency coherence of the modes of FP laser by means of the frequency shift induced by the optical intensity modulation. Experiments show that the FP modes are partially coherent and the mode spacing is relatively fixed even when the wavelength changes with ambient temperature, bias current and other factors. Therefore, it is possible to generate stable and narrow-linewidth signals at frequencies corresponding to several mode intervals of the laser. |
| Databáze: | OpenAIRE |
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