Lossy Mode Resonance Generation on Sputtered Aluminum-Doped Zinc Oxide Thin Films Deposited on Multimode Optical Fiber Structures for Sensing Applications in the 1.55 µm Wavelength Range

In this work, we demonstrated lossy mode resonance (LMR) generation in optical fiber structures based on multimode fibers coated with aluminum-doped zinc oxide (AZO) films. AZO thin films were deposited by using radio frequency magnetron sputtering. In order to exhibit the usefulness of the LMR effect for sensing applications in optical fiber based systems, the deposition conditions of the AZO film coatings were set to obtain the second LMR order within the 1.55 µm wavelength range. An optical transmission configuration setup was used to investigate the LMR effect on fiber structures based on the use of no-core and cladding-removed multimode fibers coated with AZO films synthesized from metallic sputtering targets with different proportions of Zn:Al, 92:8% and 98:2%, at atomic concentrations. The optical and electrical/chemical features of the AZO films were characterized with UV–vis and XPS spectroscopy, respectively. The optical response of the proposed sensing configuration to refractive index (RI) variations was experimentally demonstrated. For the best approach, the sensitivity of wavelength displacement to RI variations on the liquid surrounding media was found to be 1214.7 nm/RIU

Mmi Filters Configuration For Dual-Wavelength Generation In A Ring Cavity Erbium-Doped Fibre Laser

Background: Dual wavelength laser generation has been of constant interest due to their applications in optical communications and teraheartz generation. A novel configuration for Dual-wavelength laser generation based on the use of a couple of multimode interference (MMI) filters is demonstrated in a ring cavity Erbium-doped fibre laser. Methods: The MMI filters consist of a segment of no-core fibre spliced between two SMF-28 single mode fibre segments. The MMI filters configured as a Mach-Zehnder interferometer, are used as transmission spectral filters for simultaneous generation of two laser wavelengths. An optical attenuator is used to adjust the intra-cavity losses for dual-wavelength laser generation. Results: Laser emission at 1540.4 and 1554 nm for a wavelength separation of ~13.6 nm is obtained. The laser wavelengths output power stability variations with the applied pump power is also experimentally discussed. Conclusions: The use of MMI filters in the proposed dual-wavelength laser filter is experimentally demonstrated as a reliable device for dual-wavelength generation in fibre lasers

Self-Q-Switch and CW Operation of a Tunable Dual-Wavelength Er/Yb Double-Clad Fiber Laser

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Laser Wavelength Estimation Method Based on a High-Birefringence Fiber Loop Mirror

Abstract A simple method for the estimation of the wavelength of a fiber laser system is proposed. The method is based on the use of a high-birefringence-fiber loop mirror (HBFLM). The HBFLM exhibits a periodic transmission/reflection spectrum whose spectral characteristics are determined by the length and temperature of the high-birefringence fiber (HBF). Then, by the previous characterization of the HBFLM spectral transmission response, the central wavelength of the generated laser line can be estimated. By using a photodetector, the wavelength of the laser line is estimated during an HBF temperature scanning by measuring the temperature at which the maximum transmitted power of the HBFLM is reached. The proposed method is demonstrated in a linear cavity tunable Er/Yb fiber laser. This method is a reliable and low-cost alternative for laser wavelength determination in short wavelength ranges without the use of specialized and expensive equipment

Mmi Filters Configuration For Dual-Wavelength Generation In A Ring Cavity Erbium-Doped Fibre Laser

Background: Dual wavelength laser generation has been of constant interest due to their applications in optical communications and teraheartz generation. A novel configuration for Dual-wavelength laser generation based on the use of a couple of multimode interference (MMI) filters is demonstrated in a ring cavity Erbium-doped fibre laser. Methods: The MMI filters consist of a segment of no-core fibre spliced between two SMF-28 single mode fibre segments. The MMI filters configured as a Mach-Zehnder interferometer, are used as transmission spectral filters for simultaneous generation of two laser wavelengths. An optical attenuator is used to adjust the intra-cavity losses for dual-wavelength laser generation. Results: Laser emission at 1540.4 and 1554 nm for a wavelength separation of ~13.6 nm is obtained. The laser wavelengths output power stability variations with the applied pump power is also experimentally discussed. Conclusions: The use of MMI filters in the proposed dual-wavelength laser filter is experimentally demonstrated as a reliable device for dual-wavelength generation in fibre lasers

Tunable Dual-Wavelength Thulium-Doped Fiber Laser Based on FBGs and a Hi-Bi FOLM

A tunable dual-wavelength thulium doped fiber laser is demonstrated experimentally. For the first time for the 2-μm wavelength band we propose the independent tuning of the generated laser lines based on fiber Bragg gratings and the use of a Hi-Bi fiber optic loop mirror for the fine adjustment of the cavity losses to obtain stable dual-wavelength operation. Dual- wavelength laser generation with the laser lines separation in the range from 0.3 to 6.5 nm is obtained. The laser emission exhibits an optical signal-to-noise ratio better than 56 dB. Improved stability with output power fluctuations less than 1 dB is observed in dual-wavelength generation with equal power of line

All-Fiber Laser Curvature Sensor Using an In-Fiber Modal Interferometer Based on a Double Clad Fiber and a Multimode Fiber Structure

An all-fiber curvature laser sensor by using a novel modal interference in-fiber structure is proposed and experimentally demonstrated. The in-fiber device, fabricated by fusion splicing of multimode fiber and double-clad fiber segments, is used as wavelength filter as well as the sensing element. By including a multimode fiber in an ordinary modal interference structure based on a double-clad fiber, the fringe visibility of the filter transmission spectrum is significantly increased. By using the modal interferometer as a curvature sensitive wavelength filter within a ring cavity erbium-doped fiber laser, the spectral quality factor Q is considerably increased. The results demonstrate the reliability of the proposed curvature laser sensor with advantages of robustness, ease of fabrication, low cost, repeatability on the fabrication process and simple operation