Optical analog-to-digital converter
| DWPI Title: Optical analog-to-digital converter for converting optical analog signal to optical digital signal, has optical thresholding element receiving optical output signal from interferometer and generating one of bits of optical digital signal |
| Abstract: An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially. |
| Use: Optical analog-to-digital converter for converting an optical analog signal to an optical digital signal for transmitting data through an optical fiber. |
| Advantage: The converter can be formed as photonic integrated circuit (PIC), which provides each bit of the optical digital signal to be spatially separated so that each bit of the optical digital signal can be directed into a different optical fiber for parallel data transmission. The converter utilizes an optical waveguide combiner so as to generate a serial optical output by interleaving various bits of the optical digital signal. |
| Novelty: The converter (10) has channels (16) formed on a semiconductor substrate (12). An optical waveguide interferometer (22) i.e. Mach-Zehnder interferometer, includes waveguide arms (26), where a sampling optical signal (110) is split into each waveguide arm. The interferometer generates an optical output signal by combining the optical signal from the waveguide arms. An optical thresholding element (24) receives the output signal from the interferometer, and generates one of the bits of an optical digital signal (14). The substrate comprises indium phosphide or gallium arsenide. |
| Filed: 2/29/2008 |
| Application Number: US200839931A |
| Tech ID: SD 10743.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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