Femtosecond pulse shaping for synthesis, processing, and time-to-space conversion of ultrafast optical waveforms

Weiner, A.M.; Kan'an, A.M.

doi:10.1109/2944.686738

Cited by 65 publications

(22 citation statements)

References 84 publications

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“…In an effort to alleviate the requirements on electronic processing, optical pulse shaping has been widely deployed for communications applications. The desired waveform is synthesized by parallel modulation of the optical spectral components that make up the ultra-short pulse; this is achieved in a zero-dispersion pulse compressor consisting of two diffraction grating and achromatic lens pairs arranged in the 4-F optical scheme [11][12][13].…”

Section: Multirate Rz Communicationsmentioning

confidence: 99%

Multirate RZ communications for dispersive wireless optical channels

Hamzeh

Kavehrad

2006

Wireless Sensing and Processing

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Free Space Optical Communications through cloud-obscured channels suffer from severe degradations due to multiscattering, which induces delay spread in the received signal. The delay spread of FSO channel can vary considerably according to channel conditions, varying from nanoseconds to microseconds for clear and cloudy channel, respectively. In this paper, we present the use of return-to-zero (RZ) modulation in conjunction with multirate modulation schemes as viable means for minimizing the dispersive effects of the channels. We show that multirate communications provide diversity against channel degradation and fluctuation, while RZ modulation is more robust to dispersive channels than non return-to-zero (NRZ) modulation, thus providing an overall improvement in system performance, reliability and availability. INTRODUCIONWireless optical communications is one of the most promising candidates for future broadband communications, offering transmission rates far beyond possible by RF technology. Free Space Optical communications through cloud obscured channels suffer from severe degradations due to the multiscattering, which induces delay spread in the received signal. Even in the presence of clouds, large bandwidth values are attainable as suitable for high rate communications, and this bandwidth can vary widely even within the same class of clouds [1]. The delay spread of FSO channel can vary considerably according to channel conditions, varying from nanoseconds to microseconds in clear and cloudy channel conditions, respectively. The change in channel conditions can occur gradually as in the case of a cloud overcast clearing off, or abruptly as in the case of scattered clouds.These observations provide a strong motivation to research wireless optical communications systems that can provide reliable communications under such conditions. In order to maximize channel throughput, powerful modulation schemes need to be employed and provide reliable communications. Multirate communications using fractal modulation has received wide attention in the research community, as an efficient mean to provide reliable communications. Additionally, optimum pulse shaping has been shown to be a crucial element in optimizing system performance.In this paper, we present a new approach to wireless optical communications, where we combine multi-rate communications with short-pulsed RZ modulation. We show that multi-rate communications provide diversity against channel degradation and fluctuation, while RZ modulation is more robust to dispersive channels than NRZ modulation, thus providing an overall improvement in the system performance, reliability and availability. This paper is organized as follows; in section 2 we present the outdoor wireless optical channel, in section 3 we present a wireless optical system using fractal modulation and investigate its bit error rate (BER) performance. In section 4, we introduce a return-to-zero multirate wireless optical system and investigate its performance. Finally, in section 5 we compare t...

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Section: Multirate Rz Communicationsmentioning

confidence: 99%

Multirate RZ communications for dispersive wireless optical channels

Hamzeh

Kavehrad

2006

Wireless Sensing and Processing

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“…Once again, assuming a linear mask filtering and zero-dispersion pulse shaper, the output pulse train from the FEQ can be expressed by (14) and (15), where ) (t q or ) ( r kf Q represents the mask functioning as frequency domain equalizer (FEQ). …”

Section: Extension To Frequency Domain Equalization 1) Mask Designmentioning

confidence: 99%

Frequency domain equalization of optical channel distortion in free-space optical wireless communications

Kavehrad

Lee

2006

SPIE Proceedings

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In digital communications, as an alternative to conventional time domain equalization (TEQ), frequency domain equalization (FEQ) has been of interest, in particular for OFDM. In any optical channels, such as in fiber optic transmission or free-space optical communications (FSO), there can be channel dispersion, causing intersymbol interference (ISI). One feasible solution to this is FEQ of the distorted light signal by established theory of equalization. A new idea is presented that examines possibility of adaptive optical frequency-domain pulse shaping and equalization to remedy the optical channel dispersion problem in the light spectral domain.

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“…20 Ultrafast pulse shaping has also been applied to multidimensional spectroscopy techniques [21][22][23][24] as well as telecommunications systems. 25,26 While initial ultrafast pulse shaping experiments were based on temporal shaping of linearly polarized optical pulses, control of the temporal evolution of the polarization state provides further opportunities. Polarization control offers new possibilities for nonlinear interactions, [27][28][29] coherent control of molecules, 30,31 molecular spectroscopy, [32][33][34] multidimensional spectroscopy, 24,35,36 and for nanoscale interactions.…”

Section: Introductionmentioning

confidence: 99%

“…Polarization control offers new possibilities for nonlinear interactions, [27][28][29] coherent control of molecules, 30,31 molecular spectroscopy, [32][33][34] multidimensional spectroscopy, 24,35,36 and for nanoscale interactions. [37][38][39] The majority of ultrafast pulse shaping technology is based on a Fourier-domain technique introduced by Heritage et al 25,26,40 Linearly polarized ultrafast laser pulses have been programmably controlled with liquid crystal ͑LC͒ spatial light modulators ͑SLMs͒, 25 acousto-optic modulators, 41 and deformable mirrors. 6 Amplitude and phase control with SLM pulse shapers, initially demonstrated with a dual-layer SLM mask, 42 utilizing a single high spatial resolution SLM 43 or a two-dimensional SLM 44 greatly simplifies pulse shaping architectures.…”

Section: Introductionmentioning

confidence: 99%

Simplified ultrafast pulse shaper for tailored polarization states using a birefringent prism

Kupka

Schlup

Bartels

2009

Review of Scientific Instruments

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A new polarization pulse shaping method utilizing a birefringent prism as both the spectrally dispersing and polarization separating element is presented and analyzed. The method of appropriate prism design is first examined, followed by calibration technique and experimental demonstration of the pulse shaper. Using phase-only modulation by means of a spatial light modulator, we obtain near-transform limited pulses. Furthermore, a sinusoidal spectral phase imparted on the pulse is retrieved and qualitatively compares well with the theoretical target field.

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Femtosecond pulse shaping for synthesis, processing, and time-to-space conversion of ultrafast optical waveforms

Cited by 65 publications

References 84 publications

Multirate RZ communications for dispersive wireless optical channels

Multirate RZ communications for dispersive wireless optical channels

Frequency domain equalization of optical channel distortion in free-space optical wireless communications

Simplified ultrafast pulse shaper for tailored polarization states using a birefringent prism

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