1064 nm InGaAsP multi-junction laser power converters via reverse-bias method

Laser power converters (LPCs) are key to improving wireless energy transmission efficiency. We designed and fabricated single- and multi-junction 1064 nm laser power converters on InP substrates. By optimizing the tunnel junction, the double-junction laser power converter achieved 45.7% efficiency at an operating temperature of 10℃ and an incident laser power of 11.504 W/cm², while the six-junction reached 39.8% at 7℃ and 30.6 W/cm². A systematic design optimization approach for multi-junction LPCs was demonstrated through reverse-bias analysis of the current mismatch. Using this method, the InGaAsP absorption coefficient (∼1.41 × 10⁴ cm^-1) was extracted. Based on the recalculated absorption coefficient, the subcell thicknesses were redesigned and tunnel junction growth was further optimized, raising the six-junction efficiency to 42.4% at 5°C and 28 W/cm².