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ABSTRACT: We present an approach to implementing three-input addition and subtraction of quaternary base numbers in the optical domain using multiple non-degenerate four-wave mixing (FWM) processes in a single highly nonlinear fiber (HNLF) and differential quadrature phase-shift keying (DQPSK) signals. By employing 100-Gbit/s three-input return-to-zero DQPSK (RZ-DQPSK) signals (A, B, C), we demonstrate 50-Gbaud/s three-input quaternary hybrid addition and subtraction (A + B-C, A + C-B, B + C-A). Moreover, by adding a conversion stage from C to -C via conjugated degenerate FWM, we also demonstrate 50-Gbaud/s three-input quaternary addition (A + B + C). The power penalties of three-input quaternary addition and subtraction (A + B-C, A + C-B, B + C-A, A + B + C) are measured to be less than 6 dB at a bit-error rate (BER) of 10<sup>-9</sup>. In addition, no significant degradations are observed for RZ-DQPSK signals (A, B, C or -C) after the operations of quaternary addition and subtraction.
Optics Express 01/2013; 21(1):488-99. · 3.59 Impact Factor
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ABSTRACT: Fast reconstruction of the whole Brillouin gain spectrum is experimentally demonstrated using sweep-free Brillouin optical time-domain analysis (SF-BOTDA). Strain variations with the frequencies up to 400Hz are spectrally analyzed, achieving strain sensitivity of 1 microstrain per root Hz at a sampling rate of 5.5kHz and a spatial resolution of 4m. The results favorably compare with fiber Bragg grating sensing.
Optics Express 12/2012; 20(26):B581-F586. · 3.59 Impact Factor
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Irfan M Fazal,
Nisar Ahmed,
Jian Wang,
Jeng-Yuan Yang,
Yan Yan,
Bishara Shamee, Hao Huang,
Yang Yue,
Sam Dolinar,
Moshe Tur,
Alan E Willner
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ABSTRACT: We demonstrate a 2 Tbit/s free-space data link using two orthogonal orbital angular momentum beams each carrying 25 different wavelength-division-multiplexing channels. We measure the performance for different modulation formats, including directly detected 40 Gbit/s nonreturn-to-zero (NRZ) differential phase-shift keying, 40 Gbit/s NRZ on-off keying, and coherently-detected 10 Gbaud NRZ quadrature phase-shift keying, and achieve low bit error rates with penalties less than 5 dB.
Optics Letters 11/2012; 37(22):4753-5. · 3.40 Impact Factor
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ABSTRACT: Subchannel data updating of high-order modulation format signals using cascaded sum- and difference-frequency generation in a single periodically poled lithium niobate waveguide is demonstrated. One quadrature phase-shift-keying subchannel of a 16-quadrature amplitude modulation (QAM) signal at 40 Gbit/s is successfully updated, with an optical signal-to-noise ratio (OSNR) penalty of ∼2 dB for return-to-zero and ∼4 dB for non-return-to-zero at a bit-error rate (BER) of 2×10<sup>-3</sup>. Simultaneous processing of four wavelength-multiplexed 16-QAM signals with an average OSNR penalty of 4.5 dB at a BER of 2×10<sup>-3</sup> is also demonstrated.
Optics Letters 11/2012; 37(21):4365-7. · 3.40 Impact Factor
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ABSTRACT: We propose an approach to efficiently generate and multiplex optical orbital angular momentum (OAM) modes in a fiber with a ring refractive index profile by using multiple coherent inputs from a Gaussian mode. By controlling the phase relationship of the multiple inputs, one can selectively generate OAM modes of different states l. By controlling both the amplitude and phase of the multiple inputs, multiple OAM modes can be generated simultaneously without additional loss coming from multiplexing. We show, by simulation, the generation of OAM modes (OAM state |l|<3) with mode purity greater than 99%. The power loss of generating and multiplexing seven modes is about 35%. A transmitter for an OAM-based mode-division multiplexing system is proposed based on the discrete Fourier transform between the data carried by the multiple inputs and the data carried by the OAM modes. The experimental implementation of the proposed approach could be achieved by integrating ring fiber, multicore fiber, and photonic integrated circuit technology.
Optics Letters 09/2012; 37(17):3645-7. · 3.40 Impact Factor
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Science 08/2012; 337(6095):655-6. · 31.20 Impact Factor
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ABSTRACT: We propose As(2)S(3) ring photonic crystal fiber (PCF) for supercontinuum generation of optical vortex modes. Due to the large material index contrast between As(2)S(3) and air holes in the designed ring PCF, there is a two-orders-of-magnitude improvement of the difference between the effective refractive indices of different vortex modes compared with regular ring fiber. The design freedom of PCFs enables a low dispersion (<60 ps/nm/km variation in total) over a 522 nm optical bandwidth. Moreover, the vortex mode has a large nonlinear coefficient of 11.7/W/m at 1550 nm with a small confinement loss of <0.03 dB/m up to 2000 nm. An octave-spanning supercontinuum spectrum of the vortex mode is generated from 1196 to 2418 nm at -20 dB by launching a 120 fs pulse with a 60 W peak power at 1710 nm into a 1 cm long As(2)S(3) ring PCF.
Optics Letters 06/2012; 37(11):1889-91. · 3.40 Impact Factor
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ABSTRACT: We propose and experimentally demonstrate ultrawideband monocycle pulse generation using nondegenerate two-photon absorption in a silicon waveguide. The free-carrier absorption induced pulse tail at the rising edge of inverted probe pulse is largely compensated by the overlapped pump pulse and results in a symmetric negative monocycle pulse. A 143 ps Gaussian monocycle pulse is successfully obtained with a 131.7% fractional 10 dB bandwidth using a 68 ps pulsed pump. The 10 dB bandwidth and center frequency of the RF spectrum for the generated monocycle pulse can be largely tuned using an optical delay line. An operational bandwidth of 30 nm is demonstrated experimentally with stable performance, and larger optical bandwidth is expected.
Optics Letters 02/2012; 37(4):551-3. · 3.40 Impact Factor
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ABSTRACT: We propose a method of reconfigurable radio frequency up/downconversion using a parametric optical loop mirror. The baseband optical signal can be unconverted to a carrier-suppressed radio-over-fiber signal at a wide range of frequencies without the help of optical filters to remove the optical carrier. Upconversion of up to 60 GHz and downconversion from 40 GHz for both single-channel and wavelength-division-multiplexing signals using the same setup are demonstrated.
Optics Letters 12/2011; 36(23):4593-5. · 3.40 Impact Factor
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ABSTRACT: We propose a reconfigurable Tbit/s network switching element using double-pass liquid crystal on silicon (LCoS) technology accompanied by bidirectional degenerate four-wave mixing (FWM) in a single highly nonlinear fiber (HNLF). We demonstrate the LCoS + HNLF-based 2.3-Tbit/s multi-functional grooming switch which performs simultaneous selective add/drop, switchable data exchange, and power equalization, for 23-channel 100-Gbit/s return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) signals. Less than 1.5-dB power penalty is observed for power equalization at a bit-error rate (BER) of 10⁻⁹. Selective single-/two-channel add/drop are achieved with power penalties less than 1.2 dB. Switchable two-channel data exchange and simultaneous six-channel data exchange are implemented with power penalties less than 5 dB.
Optics Express 09/2011; 19(19):18246-52. · 3.59 Impact Factor
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Xue Wang,
Yang Yue,
Lin Zhang, Hao Huang,
Yan Yan,
Weijian Yang,
J. Ferrara,
V. Karagodsky,
C. Chase,
M. Tur,
C.J. Chang-Hasnain,
A.E. Willner
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ABSTRACT: A low insertion loss optical coupler is designed using chirped high-contrast-grating hollow-core waveguide. 100% tuning of power coupling ratio is realized through mechanically adjusting the waveguide height by ~3 μm.
Lasers and Electro-Optics (CLEO), 2011 Conference on; 06/2011
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ABSTRACT: We propose a simple approach to performing simultaneous multi-channel data exchange using bidirectional degenerate four-wave mixing (FWM) in a single highly nonlinear fiber (HNLF) assisted by optical filtering. Data exchange between two-channel 100-Gbit/s return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) signals with a variable channel spacing is implemented with a power penalty of less than 4.2 dB at a bit-error rate (BER) of 10(-9). Moreover, simultaneous ITU-grid-compatible four-channel 100-Gbit/s RZ-DQPSK data exchange is demonstrated with a power penalty of less than 4.7 dB at a BER of 10(-9).
Optics Express 02/2011; 19(4):3332-8. · 3.59 Impact Factor
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ABSTRACT: 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). Moreover, we investigate the impact of the temporal pump phase misalignment on the exchange performance and the dynamic range of the input signal power for the 100-Gbit/s RZ-DQPSK data exchange. The tolerance of the temporal pump phase misalignment is assessed to be +/-2 ps. An approximate 20-dB dynamic range of the input signal power is achieved.
Optics Express 11/2010; 18(23):23740-5. · 3.59 Impact Factor
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ABSTRACT: We report phase-transparent DQPSK data exchange using parametric depletion in a highly nonlinear fiber. 100-Gbit/s DQPSK data exchange is demonstrated with a power penalty less than 5dB. Pump misalignment tolerance (+/-2ps) and input signal power dynamic range (~20dB) are investigated.
Optical Communication (ECOC), 2010 36th European Conference and Exhibition on; 10/2010
