Design and characterization of multijunction photovoltaic laser power converters for nonuniform irradiance light profiles

Nonuniform irradiance profiles of lasers used in power-by-light systems deteriorate the efficiency of photovoltaic laser power converters. We analyze three approaches to deal with this efficiency loss: (1) to design the power converter front grid for the nonuniform light received from the power-by-light system; (2) to strengthen the peak current and decrease the series resistance of tunnel junctions; and (3) to homogenize the light spot impinging the power converter by simply distancing it from the laser fiber. In the context of these approaches, this paper tackles the optimization of multijunction photovoltaic laser power converters to achieve their maximum efficiency under nonuniform irradiance profiles, without using any optical element to homogenize them and, this way, reproducing realistic operating conditions. As a direct application of the design shown in this paper, we have increased the experimental efficiency of our GaAs devices by up to 3% absolute for a nominal laser wavelength of 857 nm.

Automated summary

In order to improve the efficiency of photovoltaic laser power converters, this paper analyzes three approaches: (1) designing the power converter front grid to adapt to the nonuniform light received; (2) strengthening the peak current and decreasing the series resistance of tunnel junctions; and (3) homogenizing the light spot by distancing it from the laser fiber. The paper focuses on the optimization of multijunction photovoltaic laser power converters under nonuniform irradiance profiles, without using any optical element for homogenization, and achieves realistic operating conditions. The experimental efficiency of GaAs devices has been increased by up to 3% for a laser wavelength of 857 nm.