Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

Olmedo, Miguel Iglesias; Pang, Xiaodan; Schatz, Richard; Ozoliņš, Oskars; Louchet, Hadrien; Zibar, Darko; Jacobsen, Gunnar; Monroy, Idelfonso Tafur; Popov, Sergei

doi:10.3390/photonics3020039

Cited by 7 publications

(4 citation statements)

References 23 publications

(25 reference statements)

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“…There exist multiple alternatives to perform all electronic impairment mitigation 22 . In this section, without loss of generality, we will consider the most commonly used system configuration with post reception impairment mitigation using digital signal processing.…”

Section: Resultsmentioning

confidence: 99%

Laser Frequency Noise in Coherent Optical Systems: Spectral Regimes and Impairments

Kakkar

Navarro

Schatz

et al. 2017

Sci Rep

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Coherent communication networks are based on the ability to use multiple dimensions of the lightwave together with electrical domain compensation of transmission impairments. Electrical-domain dispersion compensation (EDC) provides many advantages such as network flexibility and enhanced fiber nonlinearity tolerance, but makes the system more susceptible to laser frequency noise (FN), e.g. to the local oscillator FN in systems with post-reception EDC. Although this problem has been extensively studied, statistically, for links assuming lasers with white-FN, many questions remain unanswered. Particularly, the influence of a realistic non-white FN-spectrum due to e.g., the presence of 1/f-flicker and carrier induced noise remains elusive and a statistical analysis becomes insufficient. Here we provide an experimentally validated theory for coherent optical links with lasers having general non-white FN-spectrum and EDC. The fundamental reason of the increased susceptibility is shown to be FN-induced symbol displacement that causes timing jitter and/or inter/intra symbol interference. We establish that different regimes of the laser FN-spectrum cause a different set of impairments. The influence of the impairments due to some regimes can be reduced by optimizing the corresponding mitigation algorithms, while other regimes cause irretrievable impairments. Theoretical boundaries of these regimes and corresponding criteria applicable to system/laser design are provided.

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Section: Resultsmentioning

confidence: 99%

Laser Frequency Noise in Coherent Optical Systems: Spectral Regimes and Impairments

Kakkar

Navarro

Schatz

et al. 2017

Sci Rep

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“…The phase noise of a laser can be characterized by its frequency noise PSD, which is the spectrum of instantaneous frequency fluctuations. For a monolithic integrated semiconductor laser, its single-sided frequency noise PSD can be modeled as [11] :…”

Section: Laser Phase Noise Characterizationmentioning

confidence: 99%

Influence of laser phase noise on photonics-aided terahertz wireless communication system

Xin,

Zhang,

Zhu

2023

AOPC 2023: AI in Optics and Photonics

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“…Lasers suffer from frequency noise, which results from spontaneous emission and carrier noise, and the spectrum purity always casts a performance limit on different applications. In coherent optical communications with high-order modulation format, laser phase noise disperses the constellation and causes bit error [1][2][3]. In atomic sensing, laser frequency noise converts to amplitude noise after interaction with atom gas, limiting the stability or sensitivity of atomic sensors [4,5].…”

Section: Introductionmentioning

confidence: 99%

Linewidth Narrowing of Mutually Injection Locked Semiconductor Lasers with Short and Long Delay

Xiong

Sun

et al. 2019

Applied Sciences

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A simple and effective approach to semiconductor laser linewidth narrowing via mutual injection locking is proposed and demonstrated in both short and long delay regimes. A theoretical analysis is presented to investigate the linewidth behavior of semiconductor lasers under mutual injection locking. Experimental demonstrations in short and long delay regimes are implemented by integrated devices and a fiber link system, respectively. Locking condition and dependence of laser linewidth on coupling parameters in both regimes are studied, confirming mutual injection locking as a practical method for linewidth narrowing. For the short-delayed integrated lasers, a linewidth narrowing factor of 13 is demonstrated and sub-MHz linewidth is achieved, while for the long-delayed lasers coupled by fiber link, the intrinsic linewidth is reduced to sub-100 Hz.Recent research centers on the realization techniques of self-injection, such as low loss Si [11,12] or Si 3 N 4 [13,14] ring resonator, fiber components based feedback circuit [15,16], assembled confocal Fabry-Perot (FP) cavity [17] and CaF 2 cavity [18]. These structures rely on high Q cavity or multiple mode selection components.In this work, we propose and demonstrate a simple but effective approach to linewidth narrowing based on mutual injection locking (MIL) of semiconductor lasers. Previous research on mutual coupling mainly focuses on the nonlinear dynamics [19,20], which can be exploited to realize random sequences generation [20], chaos synchronization [21,22], modulation characteristics enhancement [23] and photonic microwave generation [24]. In addition, it is also used for coherent combining [25,26] and lasing threshold reduction [27]. However, to the best of our knowledge, there have been relatively few reports on laser linewidth or frequency noise characteristics upon mutual injection locking.A systemic study on the linewidth narrowing mechanism, locking condition and frequency noise reduction is carried out in the investigation. Modified mutual coupling rate equations incorporating Langevin noise sources are presented to analyze the mechanisms for frequency noise reduction of mutually injection locked lasers. Previous experiments indicate that laser behaves differently for short delay (τ d < 1/f RO ) and long delay (τ d > 1/f RO ) [19,20,28], where τ d is the coupling delay time and f RO represents the relaxation oscillation frequency. Therefore, experiments are carried out in both regimes: monolithically integrated mutually coupled Distributed Feedback(DFB) lasers are employed to investigate frequency noise performance in short delay regimes, while a fiber link based system is adopted for the study of long delay regimes. Locking condition and the dependence of laser frequency noise on system parameters are investigated in both regimes, confirming mutual injection locking as a practical method for linewidth narrowing.This paper is organized as follows. In Section 2, a theoretical model is presented to clarify the frequency noise suppression in mutually in...

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Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

Cited by 7 publications

References 23 publications

Laser Frequency Noise in Coherent Optical Systems: Spectral Regimes and Impairments

Laser Frequency Noise in Coherent Optical Systems: Spectral Regimes and Impairments

Influence of laser phase noise on photonics-aided terahertz wireless communication system

Linewidth Narrowing of Mutually Injection Locked Semiconductor Lasers with Short and Long Delay

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