Shaping 800 nm pulses of Yb/Tm co-doped laser: A control theoretic approach

Abstract

Modern literature has demonstrated the use of fluorescent probes in optical microscopy. Most recently, Ytterbium (Yb3+) and Thulium (Tm3+) doped nanocrystals have been used to achieve the imaging of single upconversion nanoparticles in the Stimulated Emission Depletion (STED) microscope. However, precise control of the stimulated emission at 800 nm caused by the discharge of the metastable 3H4 energy level of the Tm3+ acceptor probe would provide enhanced imaging in modern microscopy by suppressing visible fluorescence emitted from the focal plane. In this interdisciplinary paper, Model-Free Control is combined with Sliding Control to shape 800 nm pulsed emission of the lanthanide co-doped dual-laser system. This is achieved by controlling the stimulated emission rate via automatic adjustment of the probing laser pump power. This new type of controller will not be impacted by model errors like its model-based counterparts and can be fabricated by complementary metal oxide semiconductor (CMOS) processes paving way to photonic integration. Numerical simulation of the controller is executed and shows that the error between desired pulsed emission and the system's output was below 0.0057%. Mathematical analysis of the control technique and the results obtained from numerical simulations are presented.