Clock signal generator

A device for generating a clock signal, comprising:

• first and second clock circuits configured to receive optical pulses at instants in time that are offset by a first delay, each of the first and second clock circuits including first and second photoresistors and the photoresistors of the first and second clock circuits being coupled to first and second capacitive output nodes, respectively, and the first and second clock circuits configured generate first and second electronic signals on the first and second capacitive output nodes responsive to the received optical pulses;
• and
• a flip-flop circuit having first and second inputs coupled to the first and second capacitive nodes, respectively, and having an output, the flip-flop circuit configured to generate the clock signal on an output responsive to the first and second electronic signals, and wherein the flip-flop circuit includes a differential-type logic circuit including:
• first and second current mode logic cells, each current mode logic cell including first and second differential inputs and a differential output, the first current mode logic cell including its first differential inputs coupled to receive the first electronic signal, its second differential inputs coupled to the differential outputs of the second current mode logic cell, and its differential outputs coupled to the first differential inputs of the second current mode logic cell, the second differential inputs of the second current mode logic signal coupled to receive the second electronic signal.

A method of generating a clock signal, comprising:

• receiving a first laser signal including a plurality of pulses, wherein a center wavelength of the optical pulses is substantially between 1.3 and 1.8 μm;
• splitting the first laser signal to generate second and third laser signals;
• delaying each of the second and third laser signals by different amounts to generate second and third delayed laser signals;
• providing the delayed second laser signal to a first photoresistor coupled to a first capacitive node, the first photoresistor including a germanium region doped to less than substantially 5*1016 atoms/cm3 and including two contact regions formed in the germanium region and separated by a distance of substantially between 3 and 9 μm;
• providing the delayed third laser signal to a second photoresistor coupled to the first capacitive node, the second photoresistor including a germanium region doped to less than substantially 5*1016 atoms/cm3 and including two contact regions formed in the germanium region and separated by a distance of substantially between 3 and 9 μm;
• and
• generating a first clock signal on the first capacitive node in response to variations in the values of the first and second photoresistors caused by the second and third laser signals.