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High Speed Sub-GHz Spectrometer for Brillouin Scattering Analysis
Published on: December 22, 2015
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High-speed broadband absorption spectroscopy enabled by cascaded frequency shifting loops.
Hannah M Ogden1, Joseph B Murray1, Matthew J Murray1
1U.S. Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, DC, 20375, USA.
Scientific Reports
|April 8, 2023
Summary
Cascading frequency shifting loops (FSLs) overcomes amplified spontaneous emission noise, significantly expanding the frequency scanning range for high-speed optical applications. This novel approach enables a tenfold increase in scanning range, advancing spectroscopy and optical ranging technologies.
Area of Science:
- Optics and Photonics
- Spectroscopy
- Optical Metrology
Background:
- Frequency shifting loops (FSLs) utilize fiber optic ring cavities for high-speed frequency scanning, crucial for spectroscopy and optical ranging.
- Amplified spontaneous emission noise limits the scanning range of conventional FSLs due to repeated light amplification within the cavity.
Purpose of the Study:
- To introduce and validate a cascaded FSL approach to overcome the limitations of existing FSLs.
- To significantly enhance the accessible frequency scanning range for advanced optical applications.
Main Methods:
- Development of a cascaded frequency shifting loop architecture by connecting multiple FSLs in series with distinct frequency shifts.
- Theoretical modeling to predict the potential scanning range enhancement.
- Experimental implementation of a dual-cascaded FSL system for high-speed frequency scanning.
Main Results:
- Modeling indicates a potential scanning range increase up to 1 THz, a tenfold improvement over current state-of-the-art.
- Experimental demonstration of a 200 GHz scanning range with 100 MHz steps in 10 ms using cascaded FSLs.
- Successful application of the cascaded FSL platform for absorption spectroscopy of H¹³C¹⁴N.
Conclusions:
- The cascaded FSL approach effectively mitigates amplified spontaneous emission noise, dramatically increasing the usable scanning range.
- This technology offers a substantial advancement for applications demanding precise and rapid frequency scanning.
- The enhanced operating bandwidth of cascaded FSLs opens possibilities for new high-speed spectroscopic and ranging applications.
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