Compact Narrow Linewidth Actively Q-Switched Er–Yb Double-Clad Fiber Laser

Abstract: Actively Q-switched laser operation of a narrow linewidth compact fiber laser based on an Er–Yb double-clad fiber is presented. The laser linewidth as a function of the repetition rate and the Q-switched pulses characteristics for different pump powers are experimentally analyzed. Stable Q-switched laser operation with spectral laser linewidth of 73 pm in a repetition rate range from 90 to 270 kHz is obtained. The minimum pulse duration of 178 ns, maximum peak power of 30.5 W, and maximum pulse energy of 5.4 µJ are observed. The maximum average power reached is 1.1 W. Keywords: fiber lasers; Q-switched lasers; Er–Yb double-clad fiber; fiber Bragg grating

Transverse Load and Temperature Sensing Using Multiplexed Long-Period Fiber Gratings

The simultaneous measurement of transverse load and temperature using two long-period fiber gratings multiplexed in the wavelength domain is presented experimentally. For this, a mechanically induced long-period fiber grating (MI-LPFG) and a long-period fiber grating inscribed by a continuous-wave CO2 laser (CO2 LPFG) are connected in cascade. First, the transverse load and the temperature measurements were individually performed by the multiplexed long-period fiber gratings configuration. The MI-LPFG is subject to a transverse load variation from 0–2000 g with steps of 500 g, whereas the CO2 LPFG is unloaded and they are kept at room temperature. Similarly, the CO2 LPFG is subject to a temperature variation from 30 to 110 °C by increments of 20 °C, while the MI-LPFG with a constant transverse load of 2000 g is kept at room temperature. Subsequently, the simultaneous measurement of the transverse load and the temperature is performed by the multiplexed long-period fiber grating following the steps outlined above. According to the experimental results, the transverse load and temperature measurement present high repeatability for the individual and simultaneous process. Moreover, the multiplexed LPFGs exhibit low cladding-mode crosstalk of transverse load and temperature. The coarse wavelength-division multiplexing (CWDM) of long-period fiber gratings is an attractive alternative technique in optical fiber distributed sensing applications

An Intrinsic Fiber-Optic Single Loop Micro-Displacement Sensor

A micro-displacement sensor consisting of a fiber-loop made with a tapered fiber is reported. The sensor operation is based on the interaction between the fundamental cladding mode propagating through the taper waist and higher order cladding modes excited when the taper is deformed to form a loop. As a result, a transmission spectrum with several notches is observed, where the notch wavelength resonances shift as a function of the loop diameter. The loop diameter is varied by the spatial displacement of one end of the fiber-loop attached to a linear translation stage. In a displacement range of 3.125 mm the maximum wavelength shift is 360.93 nm, with 0.116 nm/μm sensitivity. By using a 1,280 nm broadband low-power LED source and a single Ge-photodetector in a power transmission sensor setup, a sensitivity in the order of 2.7 nW/μm is obtained in ∼1 mm range. The proposed sensor is easy to implement and has a plenty of room to improve its performance

Multicore Fibers

Recent advances in fiber technology enable the fabrication of multi-core fibers tailored for various applications. Examples of multi-core fibers for ultra-high-density spatial division multiplexing in communications and for high temperature sensor applications will be presented

High Temperature Sensor Based On Supermode Interference In Multicore Fiber

A high temperature fiber optic sensor based on multicore fiber is presented. Experimental results show the sensor operating stably at temperatures up to 1000°C with the capability to multiplex sensors in a single chain

High Temperature Sensor Based On Supermode Interference In Multicore Fiber

A high temperature fiber optic sensor based on multicore fiber is presented. Experimental results show the sensor operating stably at temperatures up to 1000°C with the capability to multiplex sensors in a single chain. © 2014 OSA

High Temperature Sensor based on Supermode Interference in Multicore Fiber

A high temperature fiber optic sensor based on multicore fiber is presented. Experimental results show the sensor operating stably at temperatures up to 1000°C with the capability to multiplex sensors in a single chain

Optimization Of Multicore Fiber For High-Temperature Sensing

We demonstrate a novel high-temperature sensor using multicore fiber (MCF) spliced between two single-mode fibers. Launching light into such fiber chains creates a supermode interference pattern in the MCF that translates into a periodic modulation in the transmission spectrum. The spectrum shifts with changes in temperature and can be easily monitored in real time. This device is simple to fabricate and has been experimentally shown to operate at temperatures up to 1000°C in a very stable manner. Through simulation, we have optimized the multicore fiber design for sharp spectral features and high overall transmission in the optical communications window. Comparison between the experiment and the simulation has also allowed determination of the thermo-optic coefficient of the MCF as a function of temperature. © 2014 Optical Society of America