Efficient optical-to-terahertz conversion in large-area InGaAs photo-Dember emitters with increased indium content

Area of Science:

• Optoelectronics
• Semiconductor Physics
• Terahertz (THz) Technology

Background:

• Optical-to-terahertz (THz) conversion is crucial for various applications.
• Indium Gallium Arsenide (InGaAs) is a promising material for THz emitters.
• Photo-Dember (PD) and Lateral Photo-Dember (LPD) effects are key mechanisms for THz generation.

Purpose of the Study:

• Investigate optical-to-THz conversion in large-area, bias-free InGaAs emitters.
• Optimize InGaAs composition for enhanced THz output.
• Evaluate the performance of fabricated Lateral Photo-Dember (LPD) emitters.

Main Methods:

• Grew sub-micrometer InGaAs layers with varying indium mole fractions (x=0.37, 0.53, 0.70) on GaAs substrates using metamorphic buffers.
• Fabricated asymmetrically shaped metallic gratings on the InGaAs surface for LPD emission.
• Experimentally measured THz output energy, conversion efficiency, and generation bandwidth.

Main Results:

• Observed a strong enhancement of THz output energy with increasing indium content in InGaAs.
• Achieved high conversion efficiency (0.24e-3) and broad bandwidth (up to 6 THz) with a large-area LPD emitter (x=0.7).
• Demonstrated consistent conversion efficiency at different repetition rates (1 kHz and 200 kHz).

Conclusions:

• Large-area InGaAs emitters, particularly those with higher indium content, are effective for THz generation.
• Fabricated LPD emitters offer a convenient and competitive method for producing intense, high-repetition-rate THz pulses.
• The findings pave the way for practical applications of THz technology using efficient InGaAs-based emitters.