Zeinab Sanjabi Eznaveh

Multicore fiber sensor for high-temperature applications up to 1000°C

A novel high temperature sensor based on customized multicore fiber (MCF) is proposed and experimentally demonstrated. The sensor consists of a short, few-centimeter-long segment of MCF spliced between two standard single-mode fibers. Due to interference effects, the transmission spectrum through this fiber chain features sharp and deep notches. Exposing the MCF segment to increasing temperatures of up to 1000°C results in a shift of the transmission notches toward longer wavelengths with a slope of approximately 29  pm/°C at lower temperatures and 52  pm/°C at higher temperatures, enabling temperature measurements with high sensitivity and accuracy. Due to its compact size and mechanical rigidity, the MCF sensor can be subjected to harsh environments. The fabrication of the MCF sensor is straightforward and reproducible, making it an inexpensive fiber device.

Modal analysis of antiresonant hollow core fibers using S 2 imaging

We analyze the higher-order core mode content in various designs of antiresonant hollow core fibers using spatially and spectrally resolved imaging. Hollow core fibers have great potential for a variety of applications, and understanding their mode content is crucial for many of these. Two different designs of hollow core fibers are considered, the first with eight nontouching rings and the second with eight touching rings forming a closed boundary core. The mode content of each fiber is measured as a function of length and bending diameter. Low amounts of higher-order modes were found in both hollow core fibers, and mode specific and bending-dependent losses have been determined. This study aids in understanding the core modes of hollow core fibers and possible methods of controlling them.

Mode-selective amplification in a large mode area Yb-doped fiber using a photonic lantern

We demonstrate selective spatial mode amplification in a few mode, double-clad Yb-doped large mode area (LMA) fiber, utilizing an all-fiber photonic lantern. Amplification to multi-watt output power is achieved while preserving high spatial mode selectivity. We observe gain values of over 12 dB for all modes: LP01, LP11a, and LP11b, when amplified individually. Additionally, we investigate the simultaneous amplification of LP01+LP11a and LP11a+LP11b, and the resultant mode competition. The proposed architecture allows for the reconfigurable excitation of spatial modes in the LMA fiber amplifiers, and represents a promising method that could enable dynamic spatial mode control in high power fiber lasers.

Bi-directional pump configuration for increasing thermal modal instabilities threshold in high power fiber amplifiers

We present a time dependent computer model for modal instabilities (MI) in high power fiber amplifiers based on beam propagation method. Three regimes of temporal dynamics that are characteristic of the transfer of energy between the fundamental mode and higher order mode are captured and applied to predicting the threshold of these instabilities in absence of any frequency offset between the interfering modes. Simulation results show an increase of the instabilities threshold by a factor of approximately %30 in the case of bi-directional pump scheme with respect to the forward pump configuration. Furthermore, we estimated the MI threshold applying a coupled-mode model of thermally induced instabilities which also takes account of gain saturation to its first order approximation, and obtained reasonably good agreement with respect to our beam propagation simulation results.

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.

Low-differential modal gain multimode fiber amplifiers (Conference Presentation)

As the nonlinear capacity limit of single mode fiber (SMF) transmission systems is being approached, space-division multiplexing (SDM) in multicore fibers (MCFs) or few-mode fibers (FMFs) is currently under intense investigations to achieve ultrahigh spectral efficiency per fiber. Meanwhile, a key advantage of SDM over simply increasing the number of SMFs, is its inherent device integration and resource sharing capability. This can potentially provide significant benefits in terms of the cost per bit in future optical networks. In order to efficiently address capacity scaling in a single optical fiber, few-mode and multicore erbium-doped fiber amplifiers are being developed. Critical for the implementation of SDM amplifiers is to achieve almost the same amount of gain for all spatial channels. In this respect, we have recently demonstrated multimode fiber amplifiers, supporting >15 modes, with a maximum differential modal gain of 2 dB and negligible mode mixing.

Asymmetric Very Large Mode Area Fiber with Enhanced Higher Order Mode Delocalization

A novel very-large-mode-area asymmetric rod-type fiber was fabricated and experimentally characterized. The fiber supports effective and robust single-mode operation for a core diameter of 66μm making it attractive for high power amplifier systems.

Six mode erbium-doped fiber amplifier using mode selective photonic lantern

We demonstrate a six-mode erbium doped fiber amplifier incorporating a photonic lantern for modal gain control. Signal gains >20 dB and differential modal gain <3 dB were obtained through mode selective pumping using LP21 mode.

Modeling Mode Instabilities In High Power Fiber Amplifiers

We present a time dependent high fidelity model for modal instabilities in high-power fiber amplifiers based on a beam propagation combining local rate equations with a time-dependent temperature solver and a quantum defect heating source. Article not available.