Analog light signal based opto-electronic ring-oscillator and tunable oscillation frequency

This paper demonstrates opto-electronic ring-oscillator constructed by an odd number of opto-electronic inverters for the digital (electric) and analog (light) signals based on mixed-signal communications. The opto-electronic inverter is consisting of light-emitting and light-receiving parts which can be regarded as a digital-to-analog and an analog-to-digital converters, respectively. To investigate the light-signal processing properties, the oscillation frequency (f_osc) studies were performed by controlling three different parameters of load resistors (R_L), light wavelengths (λ), and photosensor type. The smaller R_L or the shorter λ of the light signal brings the faster f_osc in opto-electronic ring-oscillator. In addition, the photodiode-based opto-electronic ring-oscillator shows much faster signal processing characteristics than the case of CdS sensor. Our opto-electronic ring-oscillators show a wide range of tunable f_osc from 0.92 Hz to 114.42 Hz; moreover, it shows small signal-like light transfer characteristics as an analog signal process that can be useful in future opto-electronic device applications.