Sensitivity enhancement of electrooptic probing based on photonic downconversion by sideband management

An Electro-Optic Pulsed NVNA Load–Pull System for Distributed <inline-formula> <tex-math notation="LaTeX">$E$ </tex-math> </inline-formula>-Field Measurements

“…The standard system configuration uses a lock-in amplifier for single frequency E-field measurement. A photonic downconversion technique is utilised to increase the measurement sensitivity and detect the phase of the measured signal, as all of the equipment is working in a phase-locked loop configuration [27]. The use of lock-in amplifiers is not suited for pulsed signal measurements as they are measuring the root-mean-square of the voltage, while high-power microwave PAs are often operated under pulsed conditions.…”

Electro-optic probing of microwave fields using a wavelength-tunable modulation depth

“…To realize a fast EOP system with a slow detector, we have extended the resonance-based methodology, with its simplified beam path, to high-frequency sensing using a photonic-mixing technique that down-converts high-frequency information into the lowfrequency band of a slow detector. Unlike the harmonicmixing technique [3,8,19], which utilizes the harmonics of the repetition rate of a pulsed laser as a local oscillator (LO), a method proposed by Kuo [20] and improved by Sasagawa [21] has been adopted. Here, a cw laser is modulated by a conventional electro-optic modulator (EOM), which imparts a sideband onto the optical beam for use as an LO to mix down, within the EO probe, the signal frequency to an intermediate frequency (IF).…”