An all-optical frequency-upconversion based on fractional talbot effect is experimentally reported. The 2.5-Gb/s
baseband signal carried on 10GHz pulse trains is upconverted to 40GHz millimeter wave after 18.49km transmission via
repetition frequency multiplication of pulse trains. The phase noise of the 40GHz is as well as -92dBc/Hz at 10kHz
frequency detuning. This scheme can operate in 60GHz band by employing the appropriate fiber length based on
fractional talbot effect.
A high frequency optoelectronic oscillator (OEO) using only low frequency optical and microwave devices is attractive
as it provides a low cost and high quality solution at the same time. In this paper, a novel OEO scheme is reported. The
proposed optoelectronic oscillator includes a 5GHz directly modulated DFB laser, an optical circulator, a 10GHz
photodetector, a 10GHz RF amplifier, and a bandpass RF filter with a central frequency at 5GHz. The OEO oscillates at
the 5GHz and with a continuous wave injected into the directly modulated DFB laser, higher harmonics will be
generated. The harmonic order can be controlled by the frequency difference between the free running DFB laser and
injection lightwave. An optical domain combined dual-loop configuration with polarization-beam splitter and a
polarization-beam combiner is employed to suppress the sidemodes in each single loop. Experiment results are proposed
to verify the scheme, in which 40GHz microwave is obtained.
A novel scheme to realize all-optical logic gates is proposed bases on nonlinear polarization rotation (NPR) in high
nonlinear fiber (HNLF). Two optical signals A and B with return-to-zero data format are injected into the HNLF together
with a continuous wave C. Thanks to the optical power variation in HNLF, nonlinear birefringence will be induced
between the two polarization axes. Thus it results in the nonlinear polarization rotation of the lightwave in the HNLF.
Both the optical signal and continuous wave are filtered out at the output of HNLF using optical band-pass filter. By
adjusting the optical power and polarization of the optical signal as well as the polarization of the polarizer with respect
to the polarization of optical signal/continuous wave, multiple all-optical logic gates can be realized. Theoretical analysis
of the simultaneously realization of the multiple optical logic gates based on NPR in HNLF is provided. And we
demonstrated the feasibility of the scheme by realizing all optical
"and", "not", "nxor", "A•B", "A•B ", half-adder and
half-subtracter at 10Gb/s operation.
40 Gb/s optical demultiplexing with amplitude regeneration is demonstrated based on data pump fiber-optical parametric
amplification(FOPA) while a 10 GHz short pulse is used as the probe. Four 10 Gb/s output channels with at least 14 dB
extinction ratio enhancement and an average 5.5 Q factor is obtained after demultiplexing.
40-Gb/s 2-Channel all-optical 3R regeneration has been realised by a fiber optical parametric amplication(FOPA). Using
degraded data signals rather than clock as the pump, all-optical 40Gb/s 2-Chanel 3R regeneration is realized with
improved performance of eliminating the unequal suppression of noise between bit0 and bit1, which is different in
mechanism from previous regeneration schemes. Theoretical analysis of the noise suppression mechanisms under
different pump power (corresponding to "0" code or "1" code) is provided. By properly adjusting the parameters of
FOPA, amplitude noise on both "0" code and "1" code can be suppressed simultaneously. The clock extraction is based
on wavelenth conversion and a Fabry-Perot (F-P) filter with a high Q value of 1000. The theoretical analysis conclusions
are verified through experiments, and the imbalance of the 3R regeneration using fiber optical parametric amplication is
eliminated. The root mean square (RMS) jitter of the clock extracted is only 180fs. Signal to noise ratio is improved
respectively from 2.7,2.4 to 4.9,5.2.
All-optical logic NOT gate is demonstrated based on cross phase modulation in highly nonlinear fiber while using a
negatively pre-chirped pulse as the probe light, with the output logic NOT signals of improved extinction ratio.
Assessment of 10 Gb/s Operation is carried out using pulse probe with and without pre-chirping stage. At least 3 dB
extinction ratio improvement is obtained compared to the implementation using chirp free pulse probe.
KEYWORDS: Polarization, Microwave radiation, Extremely high frequency, Polarizers, Radio over Fiber, Single mode fibers, Modulation, Optical amplifiers, Oscillators, Interferometers
We propose a novel technique to achieve optical frequency up-conversion in millimeter wave band without any local
microwave oscillator. It is hard to directly get mm band carrier frequency because the efficiency of the mode-locking
decreases as the carrier frequency increases. Thanks to the dynamic charge carrier density response during the injection
locking of Febry-Perot Laser diode (FP-LD), the wavelength of the leading part of carrier will be red-shifted while that
of falling part will be blue-shifted. With a suitable negative dispersion device, the carrier will be pulse compressed and
the 2nd harmonic of the carrier will be greatly enhanced. Thus it makes the RoF frequency up-conversion in mm band
feasible. By utilizing injection locking of Febry-Perot Laser diode, a suitable negative dispersion device and polarization
interferometer, a 2.5Gb/s baseband signal is frequency up-conversed to a subcarrier modulation signal at 30.8GHz.
Radio-frequency (RF) oscillators are key components in many radio and also radio-over-fiber (RoF) systems. Here, we
propose a novel technique to extent the tunable range of the radio frequency generated by optoelectronic oscillators. The
proposed optoelectronic oscillator includes an intensity modulator, a photodetector, an optical circulator, a Febry-Perot
laser diode, and a broad band RF amplifier. All those devices compose a single feedback loop. The key device in the
system is the Febry-Perot laser. By utilizing injection locking of Febry-Perot laser diode rather than the commonly used
radio-frequency band-pass filter, a high Q microwave filter is formed in optical domain. Theoretical analysis of the
optoelectronic oscillator as well as the tunablity of microwave filter is provided. The central frequency of the microwave
filter is a function of the optical wavelength and effective injection power, i.e. the injection power at the transverse-electric
(TE) mode of the F-P laser. Thus, the central frequency of the high Q band-pass can be simply tuned by tuning
the wavelength and the injection power of the injection light. Experiment is done to verify the theoretical analysis, and a
tunable range from 11.074 GHz to 39.400GHz is demonstrated experimentally.
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