Thermal and Resistive Losses in InGaAs Metamorphic Laser (λ=1064 nm) Power Converters with over 50% Efficiency

The topic of the work is the metamorphic InGaAs heterostructure for laser power converters with lambda=1064 nm. The problem of conversion efficiency under various conditions of incident radiation is investigated: with uniform illumination with a Xe-lamp, with a continuous high-power laser, and with a pulsed laser. The thermal coefficient alpha=Delta V/Delta T of overheating is calculated for continuous laser. An increasing contribution of resistive losses, associated with the spreading resistance, for a focused laser beam (when the focus spot is smaller than the photoactive area of a sample) is discussed. It has been demonstrated that with a unfocused laser beam (the mode corresponding to the practical case of wireless energy transmission), the conversion efficiency of laser radiation is compared with the efficiency under a Xe-lamp. For laser power converters with optimal (according to calculated from spectral characteristics MCC diffusion length) thickness, the efficiency of more than 48% (lambda=1064 nm) within 1.3-13 W/cm(2) incident power was demonstrated with 50.6% maximum at 5.2 W/cm(2).