Two-photon photovoltaic effect in gallium arsenide

Area of Science:

• Optoelectronics
• Semiconductor physics
• Nonlinear optics

Background:

• Two-photon absorption (TPA) is a nonlinear optical process where a material absorbs two photons simultaneously to excite an electron to a higher energy state.
• Efficiently harvesting energy from TPA has been a challenge, limiting its practical applications.
• Gallium arsenide (GaAs) is a well-established semiconductor material with suitable properties for optoelectronic devices.

Purpose of the Study:

• To demonstrate and investigate the two-photon photovoltaic effect in a gallium arsenide waveguide-photodiode.
• To explore the feasibility of harvesting electrical power from optical energy typically lost due to TPA.
• To validate experimental findings with theoretical simulations.

Main Methods:

• Fabrication of a waveguide-photodiode structure using gallium arsenide.
• Experimental measurement of the device's response to optical excitation at 976 and 1550 nm wavelengths.
• Biasing the photodiode in its fourth quadrant to harvest generated electrical power.
• Numerical simulations employing nonlinear wave propagation in waveguides and the drift-diffusion model for carrier transport.

Main Results:

• Successful demonstration of the two-photon photovoltaic effect in the GaAs waveguide-photodiode.
• Experimental data showing electrical power generation from TPA-induced carriers.
• Experimental results closely matched simulation predictions.
• Theoretical power efficiency up to 8% predicted for optimized device designs.

Conclusions:

• The two-photon photovoltaic effect can be effectively demonstrated and utilized in GaAs waveguide-photodiodes.
• This approach offers a viable method for energy harvesting from optical losses due to TPA.
• The findings pave the way for developing novel optoelectronic devices with enhanced energy conversion efficiencies.