Abstract
We demonstrate two kinds of all-fiber frequency shifters for optical coherence detection. The mode-selective coupler (MSC) and long period fiber grating (LPFG) are cascaded with the acoustically induced fiber grating (AIFG), respectively. Due to the frequency shifting characteristics of the AIFG, the low frequency shift of less than 1 MHz is achieved by both of them. Furthermore, the mode conversion occurs only within the frequency shifter, which is capable of implementing the input and output of the core LP <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> mode. The LP <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> mode converted by MSC and LPFG is finally converted back to LP <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> mode by AIFG, and the frequency is shifted up. The structure of the two kinds of frequency shifters is simple and compact, and the signal-to-noise ratio (SNR) can reach 65 dB, which provides a feasible scheme for the coherence heterodyne detection technology of low frequency.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
