An optoelectronic mixer based on composite transparent gate InAlAs/InGaAs metamorphic HEMT

In this work, we have fabricated the first transparent gate using sputtered ITO/Au/ITO composite films InAlAs/InGaAs metamorphic HEMT (CTG-MHEMT) on GaAs substrate. The CTG-MHEMT has been demonstrated to increase front side optical coupling efficiency as an optoelectronic mixer. By optimizing the bias condition, the optoelectronic mixing efficiency can be enhanced. The photodetection mechanism of CTG-MHEMT is clarified by investigating the internal photovoltaic gain (G_pv) and photoconductance gain (G_pc). For comparison of the optical characteristics, the transparent gate MHEMT (TG-MHEMT) has been fabricated. The CTG-MHEMT as an optoelectronic mixer is a promising candidate that can simplify the base station architecture in fiber-optic microwave transmission systems.