Si/Ge Avalanche Photodiodes-Based Electrical Comb-Line Generators and Photoreceivers for Very-Fast Impulse Radio Wireless Linking

We demonstrate the novel operation of a Si/Ge-based avalanche photodiode (APD) for the direct generation of ultra-wideband (UWB) frequency comb lines for impulse radio (IR) wireless communication. By applying a dc bias (V_bias) over the breakdown voltage (V_br) of the APD, the device can exhibit a significant resonant frequency without any optical signal illumination, and function as an impact ionization avalanche transit time diode-based oscillator. Under an additional electrical intermediate frequency (IF) injection, several frequency comb lines, with a spacing equal to the IF frequency, can be derived from the second harmonic of the oscillating frequency. By mixing the output pulse train from the APD-based UWB generator with the data signal from another Si/Ge APD (on the same chip) operated in the linear mode (V_bias <; V_br), which can perform high-sensitivity optical data detection, error-free IR wireless-linking with data rate as high as 3.0 Gbit/s has been successfully achieved.