Publications by authors named "Narek Karapetyan"
Article Synopsis
- Performing pattern recognition in the optical domain can offer benefits like high-speed operation and the ability to adjust and scale based on optical wave properties.
- This study combines optical correlation with optical biasing to achieve efficient QPSK pattern recognition using direct detection, eliminating the need for complex coherent detection.
- The experimental results show successful error-free recognition of multiple QPSK patterns over 3072 symbols at different baud rates, indicating effective performance with specific power thresholding values.
Compared to its electronic counterpart, optically performed matrix convolution can accommodate phase-encoded data at high rates while avoiding optical-to-electronic-to-optical (OEO) conversions. We experimentally demonstrate a reconfigurable matrix convolution of quadrature phase-shift keying (QPSK)-encoded input data. The two-dimensional (2-D) input data is serialized, and its time-shifted replicas are generated.
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- * Researchers successfully demonstrate an optically-assisted method for averaging two 4-phase-encoded data streams at high rates of 10 and 20-Gbaud, resulting in a 7-phase-encoded output.
- * The process involves three key stages: phase encoding with an optical modulator, summation using nonlinear fiber, and multicast through a lithium niobate waveguide, with the final output showing increased error vector magnitudes and optical signal-to-noise ratio penalties.
Article Synopsis
- The study presents an experimental demonstration of an optics-based half-adder that processes two channels of 4-phase-shift-keying (4-PSK) data using nonlinear wave mixing technology.
- The system takes two sets of 4-ary phase-encoded inputs and produces corresponding outputs labeled as Sum and Carry through a nonlinear device, showcasing multiple phase levels for both inputs and outputs.
- Experimental findings indicate that the half-adder achieves specific conversion efficiencies for data outputs, with low optical signal-to-noise ratio penalties at varying symbol rates, confirming its effectiveness in high-speed optical communication.
Article Synopsis
- Space-time (ST) wave packets, which exhibit dynamic optical properties, can be created by synthesizing multiple frequency comb lines with complex spatial modes that adapt orbital angular momentum (OAM) values.
- The study explores how changing the number of frequency comb lines and the spatial mode combinations affects the tunability of these ST wave packets, achieving OAM values from +1 to +6 in a short time frame.
- Simulation results indicate that using more frequency lines can lead to narrower pulse widths for the ST wave packets, and variations in OAM values can create distinct frequency chirps at different times.
We experimentally demonstrate a 4-Gbit/s 16-QAM pilot-assisted, self-coherent, and turbulence-resilient free-space optical link using a photodetector (PD) array. The turbulence resilience is enabled by the efficient optoelectronic mixing of the data and pilot beams in a free-space-coupled receiver, which can automatically compensate for turbulence-induced modal coupling to recover the data's amplitude and phase. For this approach, a sufficient PD area might be needed to collect the beams while the bandwidth of a single larger PD could be limited.
View Article and Find Full Text PDFA technique for measuring the spectral phase of an ultrashort pulse is developed based on the dispersive Fourier transformation method, as an alternative to spectral interferometric methods. The pulse spectral phase is measured by transferring the information from the spectral to the temporal domain by stretching the pulse to reach the far field of dispersion. We have implemented the technique through sum-frequency generation by using the laser pulse as a reference and have experimentally demonstrated the direct spectral phase measurement of various amplitude-modulated pulses.
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