Narrow-linewidth tunable external cavity laser for coherent communication

Daiber, A. J.

doi:10.1109/ipcon.2014.6995441

Cited by 7 publications

(4 citation statements)

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“…We used three different lasers for our experiments: two tunable laser sources and a fiber laser. TLS1 is an Emcore tunable laser of the type found in modern day coherent communication systems [4]. The second laser, termed TLS2 is a Photonetics tunable laser which is also an external cavity laser source.…”

Section: Dsh Methodsmentioning

confidence: 99%

“…Laser phase noise is an important quantity to gauge for applications that depend on the laser phase coherence [1]- [3]. For example, optical communications systems operating using coherent detection require lasers to have sub 100 kHz linewidths [4] and coherent LIDAR [5] also requires low phase noise sources, to name just a few. The laser spectrum is ideally a Lorentzian-broadened spectrum [1] and this spectrum can be quantified by a single metric, the width of the spectrum at the full width at half-maximum (FWHM).…”

Section: Introductionmentioning

confidence: 99%

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High Precision Estimation of Laser FM-Noise Using RF Quadrature Demodulation Techniques

O’Dúill¹,

Barry²

2022

IEEE Access

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We report on a technique that uses RF quadrature demodulation to measure laser FM-noise based on a delayed self-heterodyne setup. The measurement is self-referencing and the FM-noise can be measured with high precision over a sufficiently long duration that allows us to explore the limits imposed by the delay line in the self-heterodyne setup. We perform this measurement for two external cavity lasers with linewidths of tens of kilohertz and a fiber laser with a linewidth of 20 Hz. The scheme is checked and verified by finding good agreement between the FM-noise measured from beating the two external cavity lasers and the sum of the individual FM-noise of each laser.

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Section: Dsh Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High Precision Estimation of Laser FM-Noise Using RF Quadrature Demodulation Techniques

O’Dúill¹,

Barry²

2022

IEEE Access

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“…Owing to the high integration density of SiPh, the external cavity can be extended while maintaining a small footprint. This improves the quality factor and achieves a narrow linewidth, which is a key characteristic of light sources for coherent optical communication [6,7]. Furthermore, an external cavity based on the SiPh platform provides low fabrication errors and high thermo-optic efficiency, realizing precise control of the free spectral range (FSR) and a wide tunable wavelength range.…”

Section: External Cavity Lasermentioning

confidence: 99%

A high-tolerance-multi-step-long-period diffraction grating for InP/SiPh integrated lasers

Matsuura,

Takabayashi,

Nishikawa

et al. 2024

Integrated Optics: Devices, Materials, and Technologies XXVIII

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We present a high-tolerance multi-step-long-period diffraction grating (MSLP-DG) for the integration of III-V and silicon photonics (SiPh). The MSLP-DG can be easily fabricated on III-V chips and enables efficient emission of diffraction light from the facet of III-V chips through its multi-step and long-period structure. An optical coupling is achieved by combining III-V chips with MSLP-DG and SiPh chips with conventional diffraction gratings. Compared with the direct butt-coupling scheme between waveguides, the grating coupler offers a larger beam size, allowing improved misalignment tolerance. The fabricated grating coupler demonstrates tolerances of over ±3.5 μm in both vertical and horizontal directions, enabling cost-effective passive assembly. As a proof-of-concept experiment, we fabricated and operated an InP-SiPh integrated external cavity wavelength-tunable laser (ECTL) using an MSLP-DG. This work demonstrates the potential application of the proposed MSLP-DG for the cost-effective integration of III-V and SiPh in various integrated devices.

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“…Tunable lasers are vital components within every transponder of modern coherent optical communications systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].To date, narrow linewidth tunable lasers, with linewidths~100 kHz based on thermally tuned external cavity lasers, are the tunable laser technology that dominates the market for systems with line rates of 100 Gbit/s, 400 Gbit/s and beyond [7]. The reliance on thermal tuning makes these lasers unsuitable for sub-microsecond wavelength tuning times, as demanded by state-of-the-art transponders for the next-generation passive optical networks (NG-PON2) [2,8].…”

Section: Introductionmentioning

confidence: 99%

Identifying the Contribution of Carrier Shot Noise and Random Carrier Recombination to Excess Frequency Noise in Tunable Lasers

2019

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Tunable lasers are necessary devices for modern-day telecommunications and sensing systems. Tunable lasers based on altering the refractive index of the tuning sections of distributed Bragg reflectors (DBR) by varying the injected electrical current show significantly more instantaneous random changes in the instantaneous lasing frequency (or excess FM-noise) compared to non-tunable distributed feedback lasers. We identifies shot noise and random carrier recombination as being the culprits of the excess FM-noise of DBR lasers, and demonstrated this by invoking detailed analytical and numerical analyses of the stochastic carrier fluctuations in the tuning sections, as well as a simplified quasi-static laser tuning model to convert the carrier fluctuations into random instantaneous fluctuations. We found that the spectral density of the FM-noise was mostly in the range 0.5 MHz-10 MHz, and this is in agreement with many independently published results. Our analytical treatment allowed us to conclude that it would be advantageous to reduce the refractive index dependence on the carriers in order to reduce the excess FM-noise while still maintaining the tuning functionality. The simplified numerical model allowed us to create a system simulator to help further develop signal processing techniques to counteract against these instantaneous laser frequency fluctuations.

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Narrow-linewidth tunable external cavity laser for coherent communication

Abstract: Narrow-linewidth external cavity lasers have enabled the successful deployment and build out of coherent optical communication. The strengths of this architecture and robust future are presented.

Cited by 7 publications

References 0 publications

High Precision Estimation of Laser FM-Noise Using RF Quadrature Demodulation Techniques

High Precision Estimation of Laser FM-Noise Using RF Quadrature Demodulation Techniques

A high-tolerance-multi-step-long-period diffraction grating for InP/SiPh integrated lasers

Identifying the Contribution of Carrier Shot Noise and Random Carrier Recombination to Excess Frequency Noise in Tunable Lasers

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