Measurement of Rayleigh backscatter-induced linewidth reduction

Mark, J.; Bodtker, E.; Tromborg, B.

doi:10.1049/el:19850714

Cited by 37 publications

(6 citation statements)

References 4 publications

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“…For this measurement the external-cavity laser was operating 5 mA above its 17 mA threshold, and the output power, as a zeroth-order reflection from the grating, was 0.8 mW. Two possible fits, using the standard expression for the self-heterodyne spectrum of coherent laser light with white FM noise superimposed [see ( 5 ) ] , are plotted as curves (1) and (2). The integrated spectral intensity of these fits is calibrated using the area theorem and is taken equal to that of the measured spectrum.…”

Section: Resultsmentioning

confidence: 99%

“…1. This is because for short delays the delayed optical field is almost a replica of the original and the interference has a strong coherent component, as follows from (5). For short delays, the strength of the selfheterodyne spectrum is proportional to the square of the delay time [see (5) or (6)].…”

Section: Discussed Belowmentioning

confidence: 99%

“…This is because for short delays the delayed optical field is almost a replica of the original and the interference has a strong coherent component, as follows from (5). For short delays, the strength of the selfheterodyne spectrum is proportional to the square of the delay time [see (5) or (6)]. An increase in delay time will improve the signal-to-noise ratio, but it will increase the curvature of the baseline in the self-heterodyne spectrum and thus make its interpretation less direct.…”

Section: Discussed Belowmentioning

confidence: 99%

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Excess phase noise in self-heterodyne detection

Exter

Kuppens

Woerdman

1992

IEEE J. Quantum Electron.

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Self-heterodyne detection is a popular method to determine the linewidth of a laser. However, the interpretation of self-heterodyne spectra is difficult if, apart from spontaneous emission, additional noise sources are present. Measurements on an external-cavity semiconductor laser show how, for a reiatively long delay, the high-frequency (Lorentzian) wings of the self-heterodyne spectrum are a sensitive measure for the quantum-limited (Schawlow-Townes) laser linewidth. The quantum-limited laser linewidth is shown to be inversely proportional to the output power. Values below 5 kHz are routinely measured. The full width at half maximum (FWHM) laser lineing the optical spectrum non-lorentzian and the self-heterodyne signal hard to interpret. This phase noise Often has ''few" high-frequency components so the tical spectrum will still have "Lorentzian" wings, dropping off like 1 /f2, wherefis the frequency deviation from line center, but its peak will be flattened and broadened.We have studied these issues experimentally for light from an extemal-cavity semiconductor laser. The heterodyne Spectrum of this laser light could not be fitted width is larger than this due to excess low-frequency fluctuations, which are shown to result from the presence of side modes.

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Section: Resultsmentioning

confidence: 99%

Section: Discussed Belowmentioning

confidence: 99%

Section: Discussed Belowmentioning

confidence: 99%

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Excess phase noise in self-heterodyne detection

Exter

Kuppens

Woerdman

1992

IEEE J. Quantum Electron.

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“…However, the models developed so far describing the effects produced by optical feedback under laser current modulation, are not referred to RB, since they consider only the reflection coming from a single external cavity [19]- [21], typically put on the back-facet of the laser. At the same time, the effects produced by RB feedback have been considered only with reference to the linewidth reduction [22] and optical frequency shift and hopping [23], [24], in all cases for continuous-wave operation, without considering the presence of a modulating current.…”

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confidence: 99%

Optimal Configuration Mitigating Rayleigh-Backscattering-Induced Distortion in Radioastronomic Optical Fiber Systems

Nanni
¹
,

Giovannini
²
,

Lenzi³

et al. 2022

J. Lightwave Technol.

1
0
0
0

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In the context of Radioastronomic applications where the Analog Radio-over-Fiber technology is used for the antenna downlink, detrimental nonlinearity effects arise because of the interference between the forward signal generated by the laser and the Rayleigh backscattered one which is re-forwarded by the laser itself toward the photodetector.The adoption of the so called dithering technique, which involves the direct modulation of the laser with a sinusoidal tone and takes advantage of the laser chirping phenomenon, has been proved to reduce such Rayleigh Back Scattering -induced nonlinearities. The frequency and the amplitude of the dithering tone should both be as low as possible, in order to avoid undesired collateral effects on the received spectrum as well as keep at low levels the global energy consumption.Through a comprehensive analysis of dithered Radio over Fiber systems, it is demonstrated that a progressive reduction of the dithering tone frequency affects in a peculiar fashion both the chirping characteristics of the field emitted by the laser and the spectrum pattern of the received signal at the fiber end.Accounting for the concurrent effects caused by such phenomena, optimal operating conditions are identified for the implementation of the dithering tone technique in radioastronomic systems.

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“…The common mean of the linewidth narrowing and wavelength tuning is the employment of frequency-selective optical feedback. 1,2 The optical feedback can be formed by resonant reflection from a confocal cavity 3 and by the Rayleigh backscattering which emerged in a fiber 4,5 or in a microsphere resonator. 6 In general, all these frequency-selective elements have a free spectrum range less than that of a DL cavity, and these determine the lasing wavelength at scales of up to several gigahertz.…”

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confidence: 99%

Compact extended-cavity diode laser for atomic spectroscopy and metrology
Vassiliev
¹
,
Zibrov
²
,
Velichansky
³

2006
Review of Scientific Instruments
91
0
27
0
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We report on a compact, inexpensive, and durable extended-cavity diode laser ͑ECDL͒ of an original mechanical concept. The independent temperature control of a laser diode and an extended cavity provides a low-frequency drift. The linewidth of a few hundred kilohertz was measured by taking a beating of two identical ECDLs. The continuous tuning range of about 1 Å is achieved by the synchronous scan of two piezotransducers translating and rotating an external diffraction grating. The laser has been used in high-resolution spectroscopy, atom cooling, metrology, and precise interferometry.

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Measurement of Rayleigh backscatter-induced linewidth reduction

Cited by 37 publications

References 4 publications

Excess phase noise in self-heterodyne detection

Excess phase noise in self-heterodyne detection

Optimal Configuration Mitigating Rayleigh-Backscattering-Induced Distortion in Radioastronomic Optical Fiber Systems

Compact extended-cavity diode laser for atomic spectroscopy and metrology

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