Scott R. Nuccio

Independent and Simultaneous Monitoring of Chromatic and Polarization-Mode Dispersion in OOK and DPSK Transmission

We propose and demonstrate a novel technique for a simultaneous chromatic and first-order polarization-mode-dispersion (PMD) monitoring method using a partial bit delay Mach-Zehnder interferometer (MZI) with radio-frequency (RF) clock tone monitoring. RF clock tones at the output of the two branches of the MZI behave oppositely with increasing chromatic dispersion (CD) which improves the sensitivity of the measurement. The technique increases CD monitoring sensitivity over standard clock tone methods by a factor of two for a nonreturn-to-zero intensity modulation format and a factor of five for a differential-phase-shift-keying modulation format. The accuracy of PMD monitoring is also enhanced. Moreover, the partial bit delay allows the signal to pass through the constructive branch of the MZI with no observable degradation of the signal quality, allowing it to be normally detected by a receiver

Optically Efficient Nonlinear Signal Processing

Optical signal processing techniques employ a wide range of devices and various nonlinearities to achieve multiple network functionalities. The choice of nonlinearity can also impact the relative efficiency, both in terms of energy and material consumption, of the signal processing function being implemented. Techniques for some of the important functionalities, wavelength multicasting, wavelength-division multiplexing to time-division multiplexing, add-drop multiplexing, and wavelength exchange are compared in terms of the used optical spectrum, number of pumps required, and optical energy consumed. These include varieties of four-wave mixing, cross-phase modulation, Kerr-effect-based polarization rotation in optical fibers, and three-wave mixing in lithium niobate waveguides (WGs). Future possibilities of greener optical signal processing using on-chip WG technologies are discussed within the scope of recent developments in the dispersion tailored, highly nonlinear WGs.

640 Gbits/s photonic logic gates

We demonstrate 640 Gbits/s all-optical A AND B, and Ā AND B logic functions using pump depletion in a periodically poled lithium niobate waveguide. Bit-error-rate measurements show the effectiveness of the scheme, with a penalty of <2 dB.

Broadband Modulation Performance of 100-GHz EO Polymer MZMs

We experimentally characterize the performance of 100-GHz electro-optical polymer Mach-Zehnder modulators in both dual-drive and single-drive versions using broadband modulation. For the dual-drive version, we measure bit-error rate (BER) at 80 Gbit/s for differential phase-shift keying (DPSK) and >; 90 Gbit/s for on-off keying (OOK). The eye diagrams of 100 Gbit/s OOK and S21 measurement of up to 110-GHz further indicate a response bandwidth of >;100 GHz. Tunable-chirp operation is also demonstrated by changing the phase and amplitude of each driving signal. For the single-drive version, a BER of 10-9 is achieved for both 100-Gbit/s OOK and DPSK signals without optical or electrical equalization. The single-drive version shows a 7-dB bandwidth of >; 110-GHz and a chirp factor of as low as -0.02.

SBS-Based Fiber Optical Sensing Using Frequency-Domain Simultaneous Tone Interrogation

A frequency-sweep-free method for stimulated Brillouin scattering (SBS)-based sensing is proposed, having the potential for fast acquisition characteristics. The Brillouin gain spectrum and the Brillouin frequency shift are determined using multiple frequency tones for both the probe and pump. While in this paper, continuous wave probe and pump waves are used to prove the feasibility of the concept, an extension to fast distributed sensing, using pulsed pumps, is also described.

High-speed addition/subtraction/complement/doubling of quaternary numbers using optical nonlinearities and DQPSK signals

We propose an innovative approach to implementing multiple arithmetic functions of quaternary numbers using optical nonlinearities and differential quadrature phase-shift keying (DQPSK) signals. By adopting 100 Gbit/s DQPSK signals (A, B) and exploiting nondegenerate four-wave mixing (FWM) for addition/subtraction and degenerate FWM for complement and doubling in a single highly nonlinear fiber, we demonstrate 50 Gbaud/s simultaneous quaternary addition (A+B), dual-directional subtraction (A-B, B-A), complement (-A, -B), and doubling (2B). Power penalties less than 4 dB (addition), 3 dB (dual-directional subtraction), 2 dB (complement), and 3.1 dB (doubling) are observed at a bit-error rate of 10(-9).

640 Gb/s All-Optical Regenerator Based on a Periodically Poled Lithium Niobate Waveguide

640 Gb/s all-optical ON-OFF keying signal regeneration based on nonlinearities in a periodically poled lithium niobate (PPLN) waveguide is demonstrated and characterized. The data are transferred from the distorted original optical time division multiplexing (OTDM) signal onto a high quality and locally generated 640 GHz clock by pump depletion simultaneously operating a wavelength conversion. The thresholding behavior and the saturation effect of pump depletion in the PPLN waveguide for low and high pump power values, respectively, allow for a noise compression on the wavelength-converted replica of the original signal. The use of a stable clock with a shorter pulsewidth also allows for a sort of sampling of the original OTDM frame in the bit time center, resulting in a pulse reshaping that eliminates all noise contributions on the pulse tails. This operation produces a reduction of the original time jitter of the signal. The sampling operation also results in a compression of the new OTDM frame pulses compensating for the residual chromatic dispersion effects. After having characterized the transfer function of the proposed regeneration scheme, we evaluate its effectiveness as a function of optical signal-to-noise ratio (OSNR), pulse broadening, and time jitter of the input signal. Regeneration performance is measured in terms of bit error rate (BER) and power penalty @ BER = 10-9. Error-free operation can be recovered and maintained over an input signal OSNR range of 8 dB. This results in a BER improvement up to several orders of magnitude, obtained when the input OSNR is reduced by 20 dB with respect to the baseline. The time jitter of input signals with original jitter values from 100 to 300 fs has been reduced of nearly one order of magnitude to values lower than 40 fs. We also demonstrate that a pulse broadening up to 20% of the original pulsewidth can be compensated. Finally, wavelength tunability of the regenerator input and output signal can be, in principle, guaranteed over the whole C-band and beyond.

Free spectral range optimization of return-to-zero differential phase shift keyed demodulation in the presence of chromatic dispersion.

Optical differential phase shift keying is normally demodulated in a delay-line interferometer with a 1-bit delay such that the free-spectral-range of the demodulator is equal to the transmitted bitrate. We show using Karkunen-Loeve expansion simulation that free-spectral-range optimization leads to increased chromatic dispersion tolerances. The optimized delay inversely scales with the amount of chromatic dispersion such that a delay slightly shorter than the bit period increases tolerances with no adverse effect on the polarization-mode-dispersion tolerance or frequency offset penalty at the receiver.

Simultaneous and Independent Monitoring of OSNR, Chromatic and Polarization Mode Dispersion for NRZ-OOK, DPSK and Duobinary

We demonstrate experimentally and through simulations a simultaneous and independent monitoring of CD, PMD and OSNR using a frac14-bit delay Mach- Zehnder interferometer for NRZ-OOK, DPSK and Duobinary modulation formats.

Tunable 105 ns optical delay for 80 Gb/s RZ-DQPSK, 40 Gb/s RZ-DPSK, and 40 Gb/s RZ-OOK signals using wavelength conversion and chromatic dispersion

We demonstrate a variable, optical-delay element using tunable wavelength conversion in a periodically poled lithium niobate waveguide, dispersion-compensating fiber and intrachannel dispersion compensation. A delay of up to 105 ns is demonstrated using 80 Gb/s return-to-zero differential-quadrature phase-shift keying, 40 Gb/s return-to-zero differential phase-shift keying, and 40 Gb/s return-to-zero on-off keying modulation formats. Bit-error rates <10−9 are demonstrated for each waveform at various delay settings.