Chirp-managed directly modulated laser (CML)

Matsui, Yasuhiro; Mahgerefteh, Daniel; Zheng, Xuqiang; Liao, Chen-Hong; Fan, Z.F.; McCallion, K.; Tayebati, P.

doi:10.1109/lpt.2005.862358

Cited by 131 publications

(36 citation statements)

References 6 publications

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“…The power was partially received by a PD while the rest was sent to an optical filter to suppress the upstream signal. Under direct intensity modulation, the adiabatic chirp effects can be measured for a DFB laser, and it can induce a splitting optical spectrum [18,19]. By fixing the level '0' at À0.5 V and adjusting level '1' from 1 V to 0.4 V, the directly modulated eye diagrams show a decreased ER from 6.77 to 4.92.…”

Section: Resultsmentioning

confidence: 99%

Injection locked Fabry–Perot laser diodes for WDM passive optical network spare function

Han

Zhu

Xie

et al. 2009

Optics Communications

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Section: Resultsmentioning

confidence: 99%

Injection locked Fabry–Perot laser diodes for WDM passive optical network spare function

Han

Zhu

Xie

et al. 2009

Optics Communications

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“…Reduced chirp and improved ∼13 to 14 dB ER have been demonstrated using this approach [244,248]. More recently, direct-drive chirp-managed lasers (CMLs) [249], which incorporate periodic filters into the laser package, have demonstrated impressive 10 Gbps long-haul fiber-communication performance without dispersion compensation [250,251]. Due to the complex interaction of pulse shape, dispersion, nonlinearities, and power launched over the fiber channel, these demonstrations showed better overall link performance with poor ∼8 dB ER.…”

Section: Spectral Shapingmentioning

confidence: 99%

Laser communication transmitter and receiver design

Caplan

2007

J Optic Comm Rep

117

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Free-space laser communication systems have the potential to provide flexible, high-speed connectivity suitable for long-haul intersatellite and deep-space links. For these applications, power-efficient transmitter and receiver designs are essential for cost-effective implementation. State-of-the-art designs can leverage many of the recent advances in optical communication technologies that have led to global wideband fiber-optic networks with multiple Tbit/s capacities. While spectral efficiency has long been a key design parameter in the telecommunications industry, the many THz of excess channel bandwidth in the optical regime can be used to improve receiver sensitivities where photon efficiency is a design driver. Furthermore, the combination of excess bandwidth and average-power-limited optical transmitters has led to a new paradigm in transmitter and receiver design that can extend optimized performance of a single receiver to accommodate multiple data rates. This paper discusses state-of-the-art optical transmitter and receiver designs that are particularly well suited for average-power-limited photon-starved links where channel bandwidth is readily available. For comparison, relatively simple direct-detection systems used in short terrestrial or fiber optic links are discussed, but emphasis is placed on mature high-performance photon-efficient systems and commercially available technologies suitable for operation in space. The fundamental characteristics of optical sources, modulators, amplifiers, detectors, and associated noise sources are reviewed along with some of the unique properties that distinguish laser communication systems and components from their RF counterparts. Also addressed is the interplay between modulation format, transmitter waveform, and receiver design, as well as practical tradeoffs and implementation considerations that arise from using various technologies.

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“…The use of the mixed ASK/PSK output of a DFB laser with a phase modulation of π radians, combined with an interferometer, has been shown to significantly reduce the peak in the OSNR for a BER=10 -3 at ~1000 ps/nm seen with ASK [15]. If the interferometer is exchanged for a filter with an optimized bandwidth and frequency offset from the laser emission spectrum, then the performance can be further improved to ~3500 ps/nm tolerance or ~200 km of NDSF [16]. The use of 2 samples/bit 4-state MLSE with such a 'chirp managed laser' (CML) has been shown to increase the CD tolerance from ~4300 ps/nm to ~5300 ps/nm [17].…”

Section: A Directly Modulated Dfb Lasersmentioning

confidence: 99%

Review of Recent Progress in MLSE Receiver Technologies

Whiteaway¹,

Fludger²,

Langenbach³

et al. 2007

2007 Digest of the IEEE/LEOS Summer Topical Meetings

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MLSE offers adaptive non-linear receiver-sided equalization for channels with memory. New areas of application considered are directly modulated DFB laser, D(B/Q)PSK, and duo-binary transmission systems. Reduced computational complexity is a new research area.I. MLSE BACKGROUND An overview of FFE, DFE and MLSE [1] (maximum likelihood sequence estimator) receiver-sided equalization technologies will be presented. The use of MLSE to compensate for deterministic non-linear distortions in channels exhibiting memory [2], [3], and the importance of the Viterbi algorithm (VA) [4] will be described. The branch metrics used by the VA can be implemented using non-parametric histogram approximations to the actual PDFs, or parametric analytic closed form expressions [9]. The chromatic dispersion (CD) compensation benefits of MLSE have been experimentally demonstrated with two commercial realizations of an MLSE processor [5], [6]. A reach of 150 km has been shown for NRZ transmission using a 4-state MLSE at the receiver [5]. Training sequences can be used to establish the branch metrics in the MLSE, but in practice this adds complexity to the system and reduces the transmission capacity. An MLSE processor with automated acquisition has been developed [5], and a theoretical investigation into the design of a MLSE with blind acquisition capability has been reported [7]. The dynamic polarization mode dispersion (PMD) compensation capability has also been demonstrated by experimental results, which showed that an MLSE update rate of 2 kHz is suitable to compensate for a polarization rotation rate of up to 0.25 rad/ms with first order PMD [8]. II. NEW TRENDS IN MLSE DESIGN A. Applications requiring an increased number of statesThe ability of a MLSE to compensate for CD is related to the number of states that are used. The increasing capability of electronic processors will therefore lead to the development of MLSE processors with an increasing compensation capability. However this places increasing demands on the clock recovery, which is expected to increase in sophistication as the number of states in MLSE processors increases in the future. B. Signal statisticsThe best performance is obtained from the MLSE when the branch metrics are closely matched to the real statistical noise distribution of the signal samples. The histogrambased approach to constructing the branch metrics, used in the Viterbi trellis, requires a significant time to accumulate the data, particularly for the less probable events in the tails of the histograms. The inherent quantization also introduces performance limitations. However the branch metrics do then approach the complex measured non-central statistical noise distributions.The time delay involved in implementing this approach has driven the effort to simplify the branch metrics using analytic functions [9], [10]. A range of analytic approximations has been examined from Gaussian, to simple and non-central chi-squared functions, to the more complex Karhunen-Loeve expansion. Unfortunately these functio...

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Chirp-managed directly modulated laser (CML)

Cited by 131 publications

References 6 publications

Injection locked Fabry–Perot laser diodes for WDM passive optical network spare function

Injection locked Fabry–Perot laser diodes for WDM passive optical network spare function

Laser communication transmitter and receiver design

Review of Recent Progress in MLSE Receiver Technologies

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