Authors:
Alexandre C. T. Santos
1
;
2
;
1
;
Ricardo Ribeiro
1
;
Andrés Barbero
1
and
Cláudia Marcondes
3
Affiliations:
1
Departamento de Engenharia de Telecomunicações, Universidade Federal Fluminense (UFF), Niterói/RJ, Brazil
;
2
Instituto de Pesquisas da Marinha (IPqM), Rio de Janeiro/RJ, Brazil
;
3
Centro Federal de Educação Tecnológica Celso Suckow da Fonseca (CEFET-RJ), Rio de Janeiro/RJ, Brazil
Keyword(s):
Acoustic Communications, Michelson Interferometer, Opto-Acoustic Receiver, Modal Interferometer, Ultrasound, Modalmetric.
Abstract:
This paper describes investigations on sensitivity of modal fibre-interferometer named as “modalmetric”, which is inserted in two optical coupling circuits based on circulator and 2x2 fibre-coupler. The “modalmetric” in reflective structure is simply a single-mode fusion spliced with a short or long piece of a sensitive multi-mode fibre (s-MMF) with a cleaved or mirrored end. All the devices presented here were probed in the C-band and the tests were carried out at ~ 43 kHz frequency. By using a circulator, an increased opto-acoustic sensitivity could be reached by misalignment of a FC/PC connection in the single-mode fibre, thus suggesting the excitation of higher order modes in addition to the fundamental LP01. By using an 2x2 fibre-coupler, an in-creased sensitivity was observed when one of the arms was made more reflective from the FC/PC ferrule termination, thus suggesting a combination of modalmetric with Michelson interferometer or alternatively a type of light recycling that
oscillates between the reflective terminations. This paper also shows successful tests of acoustic transmission through a 9.5cm length metallic billet. The central motivation is future applications of the modalmetric-based devices on ultrasonic communication and monitoring through solid media.
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