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.

160 Gbit/s binary-to-quaternary amplitude shift keying encoding in the optical domain.

160 Gbit/s all-optical binary-to-quaternary amplitude shift keying format conversion is carried out in a nonlinear optical fiber. This scheme, which also acts as a 2 bit digital-to-analog convertor, has been confirmed through Q-factor measurements.

Preconversion phase modulation of input differential phase-shift-keying signals for wavelength conversion and multicasting applications using phase-modulated pumps.

We demonstrate a method to use phase-modulated pumps for multicasting of return-to-zero differential phase-shift keying (RZ-DPSK) signals. The method uses phase modulation of the input signal along with the co-phase-modulated pumps prior to wavelength conversion. Nine copies of a 50 Gbit/s RZ-DPSK data signal are generated via four-wave mixing with an average conversion efficiency of ∼0 dB.

10 Gbit/s tributary channel exchange of 160 Gbit/ssignals using periodically poled lithium niobate.

We propose and demonstrate data exchange in both the wavelength and time domains at a fine granularity, i.e., low-speed tributary channel exchange of wavelength-division multiplexed high-speed optical time-division multiplexed signals.

Optical data exchange of 100-Gbit/s DQPSK signals.

We experimentally demonstrate the phase-transparent optical data exchange between two differential quadrature phase-shift keying (DQPSK) signals by exploiting the signal depletion effect of non-degenerate four-wave mixing (FWM) in a highly nonlinear fiber (HNLF). Identical phase modulation is applied to the two pumps to suppress the stimulated Brillouin scattering (SBS) effect and enable the pump phase cancellation in the exchanged signals. Optical data exchange of 100-Gbit/s return-to-zero DQPSK (RZ-DQPSK) signals is implemented with a power penalty of less than 5 dB at a bit-error rate (BER) of 10(-9).

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.

Bit-rate-variable and order-switchable optical multiplexing of high-speed pseudorandom bit sequence using optical delays.

We experimentally demonstrate high-speed optical pseudorandom bit sequence (PRBS) multiplexing with coarse and fine bit-rate tuning capability and a switchable order using optical delays. Data multiplexing of 80 Gbit/s and 160 Gbit/s is shown, each with a tunable rate using a conversion/dispersion-based continuously tunable optical delay and tunable PRBS order with large switchable fiber delays. A 7% bit-rate tunability, i.

Phase-transparent optical data exchange of 40 Gbit/s differential phase-shift keying signals.

We report the phase-transparent optical data exchange of differential phase-shift keying (DPSK) signals by exploiting the parametric depletion of nondegenerate four-wave mixing (FWM) in a highly nonlinear fiber. Theoretical analyses of nondegenerate FWM involving two signals and two pumps are presented. Analytical solutions are derived, indicating the exchange condition and the feasibility of phase-transparent data exchange.

Orthogonal tributary channel exchange of 160-Gbit/s pol-muxed DPSK signal.

We report the orthogonal tributary channel exchange of a polarization-multiplexed (pol-muxed) differential phase-shift keying (DPSK) optical time-division multiplexed (OTDM) signal by exploiting the Kerr effect-induced nonlinear birefringence in a highly nonlinear fiber (HNLF). We first implement Kerr effect-based 40-to-10, 80-to-10, and 160-to-10 Gbit/s demultiplexing of DPSK OTDM signals with power penalties of less than 0.5, 1.

Eightfold 40-320 Gbit/s phase-coherent multiplexing and 320-40 Gbit/s demultiplexing using highly nonlinear fibers.

We experimentally demonstrate 40-320Gbit/s phase-coherent multiplexing based on cross-phase modulation and subsequent 320-40Gbit/s demultiplexing using cross-phase-modulation-induced frequency shift in highly nonlinear fibers. An average penalty of approximately 7dB at a 10(-9) bit-error rate is observed after the nonlinear processes. We also show the generation of a phase-coherent 320GHz optical pulse train.

40 Gbit/s optical data exchange between wavelength-division-multiplexed channels using a periodically poled lithium niobate waveguide.

We propose a time- and channel-selective optical data exchange between wavelength-division-multiplexed (WDM) channels by exploiting the cascaded second-order parametric nonlinear interactions in a periodically poled lithium niobate (PPLN) waveguide. It is observed that the PPLN-based optical data exchange provides nearly symmetric performance with signals located in the short- and long-wavelength ranges. Optical data exchange between two WDM channels is realized with a power penalty of less than 1.

Controllable optical demultiplexing using continuously tunable optical parametric delay at 160 Gbit/s with <0.1 ps resolution.

We experimentally demonstrate the use of continuously tunable optical parametric delay at 160 Gbit/s, based on conversion/dispersion for demultiplexing a 160 Gbit/s signal to 40 Gbit/s. A 15.2 ns delay is shown for a 160 Gbit/s signal, with <0.

Tunable 503 ns optical delay of 40 Gbit/s RZ-OOK and RZ-DPSK using a wavelength scheme for phase conjugation to reduce residual dispersion and increase delay.

We demonstrate a method for a tunable optical delay element that allows for minimal residual dispersion and double the relative delay. A tunable delay of 503 ns for 40 Gbit/s return-to-zero on-off keying and return-to-zero differential phase-shift keying is shown with a reduction in residual dispersion of approximately 95%.

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.

Time-slot interchange of 40 Gbits/s variable length optical packets using conversion-dispersion-based tunable delays.

We demonstrate tunable time-slot interchange of 40 Gbits/s optical data packets using a conversion-dispersion-based tunable optical delay element. Odd and even data packets are extracted from an input signal, delayed relative to one another in a highly dispersive medium, and then multiplexed back together. Tunability is demonstrated by operating with two different packet lengths, 182 and 288 bits/packet, and a bit error rate of <10(-9) is achieved.

Optical 10-20 and 20-40 Gbits/s pseudorandom bit sequence data multiplexing utilizing conversion-dispersion-based tunable optical delays.

We experimentally demonstrate all-optical 2(7)-1 pseudorandom bit sequence data multiplexing using wavelength conversion, interchannel chromatic dispersion, and intrachannel dispersion compensation. Bit-rate tuning capability is demonstrated with 10-20 and 20-40 Gbits/s multiplexing, achieving a bit-error rate <10(-9) for both rates.

Chromatic dispersion tolerance in optimized NRZ-, RZ- and CSRZ-DPSK demodulation.

We present the results of a comprehensive analysis optimizing the performance of DPSK systems with increased FSR and narrow optical filtering, establishing improved chromatic dispersion tolerance of NRZ-DPSK by 20%, RZ-DPSK by 71% and CSRZ-DPSK by 74% approximately. Transmitting a 40Gb/s signals on a spectrally efficient 50GHz DWDM grid still exhibit improvements of 7% for NRZ-DPSK, 37% for RZ-DPSK and 22% for CSRZ-DPSK, relative to a typical DPSK receiver. The optimized delay and optical filtering scale with the amount of chromatic dispersion.

Spectrally efficient slow light using multilevel phase-modulated formats.

A phase-preserving and spectrally efficient slow-light scheme has been proposed and demonstrated by utilizing advanced multilevel phase-modulated formats. A 60 ps symbol delay with error-free demodulation of both I and Q channels for 10 Gbit/s return-to-zero differential-quadrature-phase-shift-keyed (DQPSK) signals via a broadband stimulated Brillouin scattering-based slow-light medium is achieved experimentally. Simulation results on 20 Gbit/s DQPSK and 30 Gbit/s D8PSK propose to transmit very high spectrally efficient multilevel formats through a bandwidth-limited slow-light element.

Optical data packet synchronization and multiplexing using a tunable optical delay based on wavelength conversion and inter-channel chromatic dispersion.

10 Gb/s non-return-to-zero (NRZ) on-off keyed (OOK) optical data packets are synchronized and time-multiplexed using a 26-ns tunable all-optical delay line. The delay element is based on wavelength conversion in periodically poled lithium niobate (PPLN) waveguides, inter-channel chromatic dispersion in dispersion compensating fiber (DCF) and intra-channel dispersion compensation with a chirped fiber Bragg grating (FBG). Delay reconfiguration time is measured to be less than 300 ps.

Combination of optical and electronic logic gates for error correction in multipath differential demodulation.

We present an optical multipath error correction technique for differentially encoded modulation formats such as differential-phase-shift-keying (DPSK) and differential polarization shift keying (DPolSK) for fiber-based and free-space communication. This multipath error correction method combines optical and electronic logic gates. The scheme can easily be implemented using commercially available interferometers and high speed logic gates and does not require any data overhead therefore does not affect the effective bandwidth of the transmitted data.

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.