Showing papers on "Chirp published in 2009"
Patent•
Nike1
TL;DR: In this article, the radio tag doubles the transmitted frequency and returns the processed signal to a transceiver typically located on the player, and the currently transmitted frequency is then compared with the received frequency to obtain a difference frequency from which an apparatus may estimate the distance.
Abstract: Systems, apparatuses, and methods estimate the distance between a player and a ball by transmitting a chirp (sweep signal) to a radio tag located on the ball. During the chirp, the frequency of the transmitted signal is changed in a predetermined fashion. The radio tag doubles the transmitted frequency and returns the processed signal to a transceiver typically located on the player. The currently transmitted frequency is then compared with the received frequency to obtain a difference frequency from which an apparatus may estimate the distance. The apparatus may simultaneously receive the processed signal from the radio tag while transmitting the sweep signal.
581 citations
TL;DR: By implementing the algorithm, simulations show successful recovery of signals with sparsity levels similar to those possible by matching pursuit with random measurements, a significant improvement over existing algorithms.
290 citations
TL;DR: High signal-to-noise, high contrast multimodal imaging of live cells and tissues was achieved with pixel dwell times of 2-8 micros and low laser powers (< 30 mW total).
Abstract: We demonstrate high performance coherent anti-Stokes Raman scattering (CARS) microscopy of live cells and tissues with user-variable spectral resolution and broad Raman tunability (2500 - 4100 cm-1), using a femtosecond Ti:Sapphire pump and photonic crystal fiber output for the broadband synchronized Stokes pulse. Spectral chirp of the fs laser pulses was a user-variable parameter for optimization in a spectral focussing implementation of multimodal CARS microscopy. High signal-to-noise, high contrast multimodal imaging of live cells and tissues was achieved with pixel dwell times of 2-8 μs and low laser powers (< 30 mW total).
195 citations
TL;DR: In this article, the authors demonstrate precise linearization of ultrabroadband laser frequency chirps via a fiber-based self-heterodyne technique to enable extremely high-resolution, frequency-modulated cw laser-radar (LADAR) and a wide range of other metrology applications.
Abstract: We demonstrate precise linearization of ultrabroadband laser frequency chirps via a fiber-based self-heterodyne technique to enable extremely high-resolution, frequency-modulated cw laser-radar (LADAR) and a wide range of other metrology applications. Our frequency chirps cover bandwidths up to nearly 5 THz with frequency errors as low as 170 kHz, relative to linearity. We show that this performance enables 31-μm transform-limited LADAR range resolution (FWHM) and 86 nm range precisions over a 1.5 m range baseline. Much longer range baselines are possible but are limited by atmospheric turbulence and fiber dispersion.
159 citations
TL;DR: In this article, the authors demonstrate that mode-locking of ytterbium fiber lasers with a carbon nanotube saturable absorber can produce pulses ranging from 20 ps to 2 ns at repetition rates between 21 MHz and 177 kHz, depending on cavity length.
Abstract: We demonstrate that mode-locking of ytterbium fiber lasers with a carbon nanotube saturable absorber can produce pulses ranging from 20 ps to 2 ns at repetition rates between 21 MHz and 177 kHz, respectively, depending on cavity length. Nonlinear polarization evolution is not responsible for mode-locking. Even in the nanosecond regime, clean single pulses are observed and the pulse train exhibits low jitter. Combined with extremely large chirp, these properties are suited for chirped-pulse amplification systems.
142 citations
TL;DR: In this article, an approach to optically generating chirped microwave pulses with tunable chirp profile based on optical spectral shaping using a Sagnac loop filter incorporating a Chirped fiber Bragg grating (CFBG) and linear wavelength-to-time mapping in a dispersive element is presented.
Abstract: In this paper, we propose and demonstrate an approach to optically generating chirped microwave pulses with tunable chirp profile based on optical spectral shaping using a Sagnac loop filter incorporating a chirped fiber Bragg grating (CFBG) and linear wavelength-to-time mapping in a dispersive element. In the proposed approach, the optical power spectrum of an ultrashort optical pulse is shaped by a CFBG-incorporated Sagnac loop mirror that has a reflection spectral response with a linearly increasing or decreasing free spectral range. The spectrum-shaped optical pulse is then sent to a dispersive element to perform the linear wavelength-to-time mapping. A chirped microwave pulse with the pulse shape identical to that of the shaped spectrum is obtained at the output of a high-speed photodector. The central frequency and the chirp profile of the generated chirped microwave pulse can be controlled by simply tuning the time delay in the Sagnac loop mirror. A simple mathematical model to describe the chirped microwave pulse generation is developed. Numerical simulations and a proof-of-principle experiment are implemented to verify the proposed approach.
126 citations
TL;DR: This work describes three sampling regimes for FFT-based propagation approaches: ideally sampled, oversampled, and undersampled and describes the form of the sampled chirp functions and their discrete transforms.
Abstract: Accurate simulation of scalar optical diffraction requires consideration of the sampling requirement for the phase chirp function that appears in the Fresnel diffraction expression. We describe three sampling regimes for FFT-based propagation approaches: ideally sampled, oversampled, and undersampled. Ideal sampling, where the chirp and its FFT both have values that match analytic chirp expressions, usually provides the most accurate results but can be difficult to realize in practical simulations. Under- or oversampling leads to a reduction in the available source plane support size, the available source bandwidth, or the available observation support size, depending on the approach and simulation scenario. We discuss three Fresnel propagation approaches: the impulse response/transfer function (angular spectrum) method, the single FFT (direct) method, and the two-step method. With illustrations and simulation examples we show the form of the sampled chirp functions and their discrete transforms, common relationships between the three methods under ideal sampling conditions, and define conditions and consequences to be considered when using nonideal sampling. The analysis is extended to describe the sampling limitations for the more exact Rayleigh-Sommerfeld diffraction solution.
122 citations
TL;DR: In this paper, a compressive receiver (CR) is presented utilizing a composite right/left-handed (CRLH) dispersive delay line (DDL) for analog signal processing applications.
Abstract: A compressive receiver (CR) is presented utilizing a composite right/left-handed (CRLH) dispersive delay line (DDL) for analog signal processing applications. The CRLH DDL offers advantages such as arbitrary frequency of operation and wide bandwidth, filling a gap with competing DDL technologies. The presented CR system utilizes an impulse-driven CRLH DDL and mixer inversion for chirp generation required for real-time signal processing. At high frequencies, this eliminates frequency ramp generators. The CR is employed as a frequency discriminator and a tunable delay line with dispersion compensation. The simulation and experimental results fully validate the presented systems as proof-of-concept for high-frequency applications such as real-time Fourier transformers and signal analyzers.
106 citations
TL;DR: Comparison with analytical mode-locking theory shows a good quantitative agreement with the master equation mode- locking model for nanosecond pulse spectrogram shape and chirp.
Abstract: We evaluate the shape and chirp of nanosecond pulses from a fiber laser passively mode locked with a nanotube-based saturable absorber by using a synchronously scanning streak camera and a monochromator to directly measure the pulse spectrogram. We show that the stable sech2 output pulse possesses a predominantly linear chirp, with a residual quartic phase and low noise. Comparison with analytical mode-locking theory shows a good quantitative agreement with the master equation mode-locking model.
103 citations
16 Mar 2009
TL;DR: In this paper, it was shown that by utilizing this particular waveform structure, the energy transmitted over a pulse duration can be spread in a practically linear manner within the spatial extent specified by two angles despite the nonlinear relationship between spatial and electrical angles.
Abstract: Recently range-dependent (or time-varying) beamforming has been presented as a method to spread transmit energy over a desired spatial extent via a linear frequency shift across the waveforms transmitted at each element of an array. This element-level waveform diversity yields additional degrees of freedom relative to traditional beamforming techniques for which some sensing benefits have been suggested. In this paper, chirp waveforms with slightly different starting frequencies are analyzed to characterize the associated range-dependent beampattern. Specifically, it is determined that by utilizing this particular waveform structure, the energy transmitted over a pulse duration can be spread in a practically linear manner within the spatial extent specified by two angles despite the nonlinear relationship between spatial and electrical angles if the set of frequency-diverse chirps are appropriately parameterized. Additionally, a space-range ambiguity diagram is formulated. The ambiguity is discussed for the traditional and frequency-diverse array scenarios.
98 citations
TL;DR: A modified-Wigner-Ville distribution (referred to as M-WVD) approach is proposed, which is based on a scale transform in the time-frequency distribution plane and can effectively suppress the troublesome cross-term interference associated with WVD via coherent integration.
Abstract: Inverse synthetic aperture radar (ISAR) imaging of air, space or ship targets with complex motion has attracted the attention of many researchers in the past decade. Complex motion of targets induce cross-range scatterer-variant quadratic phase terms, which will degrade the cross-range resolution and affect focusing quality. A new algorithm is proposed for the ISAR imaging of complex moving targets. First, conventional range alignment, phase compensation and range compression are performed over the raw phase history data such that each range bin can be modelled as the sum of several linear frequency modulation or chirp signals. Secondly, a modified-Wigner-Ville distribution (referred to as M-WVD) approach is proposed, which is based on a scale transform in the time-frequency distribution plane and can effectively suppress the troublesome cross-term interference associated with WVD via coherent integration. Finally, the azimuth ISAR image can be obtained via a simple maximisation projection from the two-dimensional accumulated plot to the azimuth dimension. Compared with existing WVD-based ISAR imaging algorithms, the proposed method has the following features: better cross-term interference reduction achieved at no resolution loss, computationally more efficient with no expensive two-dimensional parameter search, and higher signal processing gain because of coherent integration during the whole imaging time. Both numerical and experimental results are provided to demonstrate the performance of the proposed method.
TL;DR: It is found that a small compromise in amplifier bandwidth relative to the full phase-matching bandwidth, through use of the appropriate seed chirp, both maximizes the efficiency-bandwidth product and optimizes the signal-to-noise ratio.
Abstract: We present general guidelines for the design of ultrabroadband, high-energy optical parametric chirped-pulse amplifiers, where maximization of both conversion efficiency and bandwidth and simultaneous suppression of superfluorescence is required. Using a semi-analytical approach together with numerical simulations, we find that the ratio of pump and seed pulse durations is a critical parameter in temporal optimization, and its optimum depends on the amplifier gain. Multi-stage amplifier design thus requires independent optimization of seed chirp at each amplification stage. We find that a small compromise in amplifier bandwidth relative to the full phase-matching bandwidth, through use of the appropriate seed chirp, both maximizes the efficiency-bandwidth product and optimizes the signal-to-noise ratio. On the other hand, maximization of signal bandwidth is found to significantly degrade both the signal-to-noise ratio and the conversion efficiency.
TL;DR: In this article, a phase-locked multicarrier light source that employs a continuous wave (CW) light source, two phase modulators, and a dispersion medium is described.
Abstract: This paper describes a phase-locked multicarrier light source that employs a continuous wave (CW) light source, two phase modulators, and a dispersion medium. A sinusoidal phase modulation (PM) with a modulation index of ?/4 and a group velocity dispersion of ±1/(4?fm 2), where fm is the modulation frequency, are applied to a CW light followed by a large sinusoidal PM. This configuration provides a multicarrier light with a flattened optical power spectrum for any modulation index of the second PM. By adopting a chirped fiber Bragg grating (FBG) as a dispersion medium instead of a long normal dispersion fiber, we can increase the stability of the optical output spectrum and reduce the size of the multicarrier light generator. We have built a prototype with this configuration that generates a 61-carrier light with a 25 GHz interval and a power deviation of less than 8 dB.
TL;DR: In this article, the results of enhanced high-order harmonic generation (HHG) in laser-produced plasmas using a two-color laser pump (98% of 800 nm and 2% of 400 nm) are presented.
Abstract: The results of enhanced high-order harmonic generation (HHG) in laser-produced plasmas using a two-color laser pump (98% of 800 nm and 2% of 400 nm) are presented. Even (up to the 38th order) and odd (up to the 45th order) harmonics of 800 nm radiation were generated in the case of a two-color orthogonal polarization pump of various plasmas. The comparison between HHGs using parallel and orthogonally polarized 400 and 800 nm radiations showed better conversion efficiency for the latter case. We have also used circularly polarized 800 nm pump for second-harmonic generation and HHG. We also present the results of the influence of the chirp and phase modulation of the fundamental radiation in laser plasma on the spectral properties of odd and even harmonics.
TL;DR: This non-trivial scaling of the effective nonlinear coefficients results from pulse compression, which further enhances the optical field beyond that of purely slow-group velocity interactions.
Abstract: We investigate the nonlinear response of photonic crystal waveguides with suppressed two-photon absorption. A moderate decrease of the group velocity (~c/6 to c/15, a factor of 2.5) results in a dramatic (×30) enhancement of three-photon absorption well beyond the expected scaling, ∝1/vg3. This non-trivial scaling of the effective nonlinear coefficients results from pulse compression, which further enhances the optical field beyond that of purely slow-group velocity interactions. These observations are enabled in mm-long slow-light photonic crystal waveguides owing to the strong anomalous group-velocity dispersion and positive chirp. Our numerical physical model matches measurements remarkably.
TL;DR: In this article, a simplified homodyne detection scheme for linear FM modulated lidar is presented in which pulse dechirping is performed in the optical domain, which removes the limit on the chirp bandwidth and enables the use of more efficient photodiodes with larger detector area.
Abstract: A simplified homodyne detection scheme for linear FM modulated lidar is presented in which pulse dechirping is performed in the optical domain. This method provides quantum limited detection sensitivity with much less receiver complexity compared to heterodyne detection systems. Another advantage of this approach is the reduced bandwidth requirement for the photodetector. This removes the limit on the chirp bandwidth, and enables the use of more efficient photodiodes with larger detector area. A field trial using a 5-in aperture diameter commercial telescope and a 370-m target range verified the sensitivity estimation and demonstrated the feasibility of this technique.
TL;DR: The proposed keystone-Wigner transform (KWT) eliminates the effects of linear frequency migration to all the signal components even if their chirp rates are unknown and can be efficiently implemented using only complex multiplications and FFT based on the scaling principle instead of interpolating.
TL;DR: A bistatic-motion error model is developed where the position deviations of the two platforms are simplified as the bistatics slant-range displacement in the zero Doppler plane and the monostatic motion-compensation technique is applied and integrated into CSA to compensate the trajectory deviations of transmitter and receiver.
Abstract: This paper discusses the processing method for bistatic SAR data in the constant-offset configuration. The constant-offset configuration is also known as the azimuth stationary or invariant configuration where transmitter and receiver follow each other, moving on identical velocity vector. In this paper, the proposed processing method for bistatic SAR data is based on Loffeld's bistatic formula that consists of two terms, i.e., the quasi-monostatic (QM) term and bistatic-deformation (BD) term. Our basic idea is to linearize the aforementioned two terms and then incorporate the BD term into the QM term to obtain an analogous monostatic spectrum. Based on the new spectrum, any efficient 2-D frequency or range-Doppler domain processor can easily be employed to process the bistatic data, where the Doppler phase parameters of the processor need to be adjusted. In this paper, we concentrate on the application of chirp-scaling-algorithm (CSA) processor. In addition, a bistatic-motion error model is developed where the position deviations of the two platforms are simplified as the bistatic slant-range displacement in the zero Doppler plane. Using this model, the monostatic motion-compensation technique is applied and integrated into CSA to compensate the trajectory deviations of transmitter and receiver. Finally, real and simulated data are used to validate the proposed processing method.
TL;DR: In this article, the authors present an efficient method to generate an ultrashort attosecond (as) pulse when a model of an ion is exposed to the combination of an intense few-cycle chirped laser pulse and its 27th harmonics.
Abstract: We present an efficient method to generate a ultrashort attosecond (as) pulse when a model ${\text{He}}^{+}$ ion is exposed to the combination of an intense few-cycle chirped laser pulse and its 27th harmonics. By solving the time-dependent Schr\"odinger equation, we found that high-order harmonic generation (HHG) from ${\text{He}}^{+}$ ion is enhanced by seven orders of magnitude due to the presence of the harmonic pulse. After optimizing the chirp of the fundamental pulse, we show that the cut-off energy of the generated harmonics is extended effectively to ${I}_{p}+25.5{U}_{p}$. As a result, an isolated 26-as pulse with a bandwidth of 170.5 eV can be obtained directly from the supercontinuum around the cut-off of HHG. To better understand the physical origin of HHG enhancement and attosecond pulse emission, we perform semiclassical simulations and analyze the time-frequency characteristics of attosecond pulse.
TL;DR: In this paper, the echo-enabled harmonic generation technique was combined with the bunch compression and allowed one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser.
Abstract: We propose a scheme that combines the echo-enabled harmonic generation technique with the bunch compression and allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. A few-cycle intense laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Sending this beam through a short undulator results in an intense isolated attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM) can be generated from a 200 nm ultraviolet seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time ($\ensuremath{\sim}24$ attoseconds) and may open a new regime of ultrafast sciences.
TL;DR: In this article, the authors proposed a coherent anti-Stokes Raman scattering (CARS) microscopy using linearly chirped femtosecond laser pulses and spectrally and time-integrated detection.
Abstract: Coherent anti-Stokes Raman scattering (CARS) microscopy using linearly chirped femtosecond laser pulses and spectrally and time-integrated detection is discussed both theoretically and experimentally. By matching the linear chirp of Stokes and pump pulses, the spectral resolution is reduced to the Fourier limit of the chirped pulse duration (spectral focusing). We discuss the effect of the time-ordering of Pump and Stokes pulses on the signal strength and selectivity, and give analytical expressions for the relevant quantities. We consider linear chirp obtained by glass elements of known group-velocity dispersion, and analyze the limit of the spectral resolution by higher order glass dispersion. Experiments corroborating the theory are presented, using 100 fs laser pulses, SF57 glass elements, and polystyrene beads as test samples.
TL;DR: In this paper, an optical approach to generating chirped microwave pulses using a photonic microwave delay-line filter (PMDLF) with a quadratic phase response was proposed.
Abstract: We propose an optical approach to generating chirped microwave pulses using a photonic microwave delay-line filter (PMDLF) with a quadratic phase response. If a chirp-free broadband microwave pulse is inputted into the filter, a chirped microwave pulse is generated thanks to the quadratic phase response of the filter. To design a PMDLF with a quadratic phase response, complex tap coefficients are required, which is hard to implement in the optical domain. In this letter, a PMDLF with equivalent complex coefficients implemented based on a nonuniformly spaced delay-line structure is demonstrated. Since only positive coefficients are required, the filter is easy to implement. A design example is provided. A five-tap PMDLF to generate a chirped microwave pulse with a chirp rate of 13.2 GHz/ns is then experimentally demonstrated.
TL;DR: In this article, a joint experimental and theoretical study on strong field photo-ionization of sodium atoms using chirped femtosecond laser pulses is presented, where different excitation pathways enabling control are identified by simultaneous ionization and measurement of photoelectron angular distributions employing the velocity map imaging technique.
Abstract: We present a joint experimental and theoretical study on strong- field photo-ionization of sodium atoms using chirped femtosecond laser pulses. By tuning the chirp parameter, selectivity among the population in the highly excited states 5p, 6p, 7p and 5f, 6f is achieved. Different excitation pathways enabling control are identified by simultaneous ionization and measurement of photoelectron angular distributions employing the velocity map imaging technique. Free electron wave packets at an energy of around 1eV are observed. These photoelectrons originate from two channels. The predominant 2+1+1 resonance enhanced multi-photon ionization (REMPI) proceeds via the strongly driven two-photon transition 4s 3s, and subsequent ionization from the states 5p, 6p and 7p whereas the second pathway involves 3+1 REMPI via the states 5f and 6f. In addition, electron wave packets from two-photon ionization of the non-resonant transiently populated state 3p are observed close to the ionization threshold. A mainly qualitative five-state model for the predominant excitation channel is studied theoretically to provide insights into the physical mechanisms at play. Our analysis shows that by tuning the chirp parameter the dynamics is effectively controlled by dynamic Stark shifts and level crossings. In particular, we show that under the experimental conditions the passage through
TL;DR: A simple analytical model of the mechanism responsible for the formation of bound states of pulses in the stretched-pulse fiber laser predicts the existence of a single bound state with a separation of the order of the pulsewidth at maximum stretch, a result consistent with simulations and experiments.
Abstract: A simple analytical model of the mechanism responsible for the formation of bound states of pulses in the stretched-pulse fiber laser is given The proposed model is based on a noncoherent interaction occurring between the pulses near their position of maximum stretch within the dispersion-managed cavity, where the pulses possess a large linear chirp This nonlinear interaction is due to the combined effects of the cross-phase modulation and the cross-amplitude modulation caused by the nonlinear gain associated with the mode-locking mechanism used in the laser This model predicts the existence of a single bound state with a separation of the order of the pulsewidth at maximum stretch, a result consistent with simulations and experiments
TL;DR: In this article, the authors demonstrate almost chirp-and pedestal-free optical pulse compression in a nonlinear fiber Bragg grating with exponentially decreasing dispersion, which can be well approximated by a few gratings with different constant dispersions, and propose a compact pulse compression scheme, which consists of a linear and nonlinear grating to effectively compress both hyperbolic secant and Gaussian shaped pulses.
Abstract: We demonstrate almost chirp- and pedestal-free optical pulse compression in a nonlinear fiber Bragg grating with exponentially decreasing dispersion. The exponential dispersion profile can be well-approximated by a few gratings with different constant dispersions. The required number of sections is proportional to the compression ratio, but inversely proportional to the initial chirp value. We propose a compact pulse compression scheme, which consists of a linear and nonlinear grating, to effectively compress both hyperbolic secant and Gaussian shaped pulses. Nearly transform-limited pulses with a negligibly small pedestal can be achieved.
TL;DR: Two algorithms based on the Memory-based architecture and the Direct Digital Synthesizer (DDS) architecture are presented and measurement results indicate that the DDS chirp generator is a preferred choice for high-resolution SAR application.
Abstract: This paper discusses the design and development of a FPGA-based chirp generator for high resolution Unmanned Aerial Vehicle (UAV) Synthetic Aperture Radar. The desired bandwidth of the chirp signal is 100MHz (combination of I and Q channels) with a chirp rate of 5MHz/"s. Two algorithms based on the Memory-based architecture and the Direct Digital Synthesizer (DDS) architecture are presented. The measurement results indicate that the DDS chirp generator is a preferred choice for high-resolution SAR application.
TL;DR: By chirping the pulses, the longitudinal range of the generated plasma channels can be extended relative to filaments generated by fully compressed, transform-limited femtosecond pulses, and there is a clear correlation between the extent of filamentation and the intensity of the on-axis emission by the femTosecond Bessel-Gauss beam.
Abstract: We report experimental results on ultrafast filamentation with temporally chirped femtosecond Bessel-Gauss beams. We find that by chirping the pulses, the longitudinal range of the generated plasma channels can be extended relative to filaments generated by fully compressed, transform-limited femtosecond pulses. We find a clear correlation between the extent of filamentation and the intensity of the on-axis emission by the femtosecond Bessel-Gauss beam. The on-axis emission is negligible for fully compressed pulses, but it can become quite substantial (up to 10% of the input pulse energy) when chirped pulses are used. Under certain conditions, the on-axis emission becomes sufficient for generating its own plasma channel thus resulting in extended filamentation. This effect may offer means of remote control over filament formation with femtosecond Bessel-Gauss beams. We identify a four-wave mixing process, enhancement of which is likely to result in a maximum of the on-axis emission, and derive a simple expression for estimating the duration of the chirped pulse that is required for such enhancement. Our estimations are in good agreement with the experiment.
TL;DR: The proposed method for the time delay yields a variance which is theoretically equal to the Cramer-Rao lower bound and the validity of this estimation method is demonstrated via simulations.
Abstract: A new time-delay estimator is presented in this paper. It is evaluated based on the delay property of the fractional Fourier transform with less computation and is suitable for chirp signals. The statistical analysis in terms of signal-to-noise ratio (SNR) and estimation accuracy for this estimation is also studied. The proposed method for the time delay yields a variance which is theoretically equal to the Cramer-Rao lower bound. The validity of this estimation method is demonstrated via simulations.
01 Jan 2009
TL;DR: In this paper, the authors investigated 40-Gb/s cost-efficient transmitter for access and metro networks, which comprises a standard directly modulated distributedfeedback (DFB) laser and a subsequent optical filter.
Abstract: We investigate 40-Gb/s cost-efficient transmitter for access and metro networks. This 40-Gb/s transmitter comprises a standard directly modulated distributed-feedback (DFB) laser and a subsequent optical filter. Large dispersion tolerance of this transmitter is realized by chirp control through the phase correlation between adjacent bits for the destructive interference in order to erase the power of "0" bits while enhancing the extinction ratio. The chirp model of the DFB laser and the optimum parameters of the optical filter have been numerically analyzed. The chirp-managed 42.8-Gb/s transmission over 20-km standard single mode fiber (SSMF or SMF-28) without dispersion compensation and a centralized lightwave WDM-PON system are experimentally demonstrated. We have also realized the transmission over 100-m graded index plastic optical fiber (GI-POF). Moreover, the application in the metro network over 240-km SSMF or SMF-28 has also been investigated in this paper.
TL;DR: In this article, a photonic microwave filter with nonlinear phase response was proposed and investigated for linearly chirped microwave pulse compression using a matched filtering method, based on optical phase to microwave phase conversion through single-sideband modulation and heterodyne detection.
Abstract: Chirped microwave pulse compression using a photonic microwave filter with nonlinear phase response to implement matched filtering is proposed and investigated. The photonic microwave filter with the required phase response is realized based on optical phase to microwave phase conversion through single-sideband modulation and heterodyne detection. A detailed theoretical analysis on the photonic microwave filter design and the linearly chirped microwave pulse compression is developed. A photonic microwave filter having a quadratic phase response with a bandwidth of 3 GHz is implemented. An application of the photonic microwave filter for linearly chirped microwave pulse compression is investigated.