Stabilized hybrid mode-locking of erbium-doped fiber laser (EDFL) by incorporating strong MoS2 saturable absorber and weak nonlinear polarization rotation (NPR) is demonstrated. At threshold condition, the MoS2 starts the mode-locking of EDFL to provide a 680 fs wide pulsewidth with a time-bandwidth product of 0.407. With only the unintentionally weak NPR effect, the fluctuated EDFL pulsewidth ranged between 377 and 382 fs is observed with a tolerant half-wave-plate orientation angle of θHWP =21°. Adding MoS2 enhances the self-amplitude modulation (SAM) and shortens a pulsewidth to 305–330 fs with an allowable θHWP increasing up to 76°, implying the enhanced stabilization of passively mode-locking in EDFL. Enduing the weak NPR with strong saturable absorption (SA) effect significantly makes up the maximal SAM coefficient from 4.02 × 10−4 to 1 × 10−3, whereas the self-phase modulation (SPM) coefficient remains unaltered as that without adding the MoS2. The MoS2 saturable absorber additively offsets SAM beyond its threshold to enlarge the polarization tolerance without altering the SPM. Adjusting the polarization controller with unintentional polarization dependence affects the NPR induced polarization dependent loss so as to strengthen the SAM for mandatory mode-locking optimization of EDFL.
Doping of semiconductors serve various purposes in metal‐oxide‐semiconductor (CMOS) technology, eg, increase carrier concentration and modify electric field distribution. With the scaling down of device and the introduction of three‐dimensional fin field‐effect transistors (FinFET), precise and reliable dopant quantification of concentration at the nano‐scale is critical. Laser‐assisted atom probe tomography (APT) provides a unique approach to characterize and quantify the dopant in three dimensions at sub‐nanometer resolution. Nevertheless, quantification accuracy of APT is strongly influenced by the experimental conditions. Although B quantification has been widely studied, the correlation of B signal loss to B concentration is not yet established. In addition, no phosphorous quantification study has been reported. In this work, we found that, due to B multi‐hit effect in APT, high B dose sample has larger B loading compared with low B dose sample. For standard calibration with minimized impact from multi‐hit effect, we recommend B dose in the range of 1e14 atoms/cm2. Despite the fact that B loading is dose dependent, APT quantification of B achieves precision within 2% to 6% relative standard deviation (RSD), which demonstrates that APT has good accuracy. On the other hand, P quantification suffers from mass interference of 31P+ and 31P22+ at 31 Da resulting in a large loading between APT and secondary ion mass spectrometry (SIMS). Nevertheless, we recommend that 31 Da to be labeled as 31P+ for smaller P variation for the APT analysis.
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