Maximum-output-power and bandwidth performances are usually two tradeoff parameters in the design of high-speed photodetectors (PDs). In this paper, we report record high-peak output voltage (∼ 30 V) together with ultrahigh-speed performance (1.8 ps, 190 GHz) observed in low-temperature-grown GaAs (LTG-GaAs)-based metal-semiconductor-metal (MSM) traveling-wave photodetectors (TWPDs) at a wavelength of 800 nm. Ultrahigh-peak output power and ultrahigh-electrical bandwidth performances were achieved due to superior MSM microwave guiding structure, short carrier trapping time, and the capability to take high bias voltage (∼ 30 V) with a LTG-GaAs layer. Under such a high bias voltage, a significant nonlinear photocurrent increase with the bias voltage was observed. The nonlinear photoconductance and ultrahigh-output power-bandwidth performances opens a new way in the application of high-performances optoelectronic mixers and photomixer devices.