Performance of ultrafast laser written active waveguides by rigorous modeling of optical gain measurements

Femtosecond laser written 16.5 mm long glass-waveguide amplifier and laser with 5.2 dB cm−1 internal gain at 1534 nm

“…At this point it is worth noting that length optimization was aimed at achieving a compact device and therefore the waveguide length finally considered was intended to achieve a compromise between internal gain per unit length and net gain. It can be seen that, for this doping level, a reduction of the coupling losses to <0.1 dB cm −1 (already achieved in this work) and passive losses to 0.4 dB cm −1 (achievable in commercial glasses [7,25]) would render net gain values above 7.5 dB for a length of 16.5 mm, in agreement with former predictions of expected performance of laser written structures in heavily doped glasses [9]. The simulated saturation profile is in excellent agreement with the experimental values for the whole pump power interval.…”

“…Internal gain experimental results were simulated following the procedure thoroughly described in [9,17]. Measured parameters, i.e.…”

“…This was done, for different slit widths, in order to ensure a set of initial processing conditions enabling a fine control of the waveguide structure, thereby tuning the mode size to minimize the coupling losses. Additionally, starting from initial small signal gain experimental results, the active parameters of the waveguides such as optimal length, gain per unit length and net gain were also simulated in order to improve their performance as optical amplifiers and to be used as a pre-design parameter in the glass making stage [9]. Hence, in this letter, the challenge of designing a multi-functional material whose functions are to produce both tunable passive and active waveguide parameters are described and its realization to an active device are demonstrated.…”

Dual Regimes of Ion Migration in High Repetition Rate Femtosecond Laser Inscribed Waveguides

“…It has to be considered though that the situation corresponds to a non-optimized sample length. Hence, we have carried out several simulations [18] to show the effect of active ion migration over the pre-designed values of an optical amplifier ( Figure 5).…”

Characterization of Active Integrated Multicore Waveguides

“…First, the active and passive characterization of the individual waveguides has been carried out [2]. Next, the parameters obtained from the characterization process are used to compare the theoretical and experimental behavior of signals propagating in waveguides with several coupled nuclei, and where the theoretical simulations are based on solving the system of equations of the propagation of optical powers coupled to the system of differential equations for the variation of the population density of the ions of the rare earths in the different energy states [3].…”