Polarization Effects on Thermally Stable Latency in Hollow-Core Photonic Bandgap Fibers

There are a host of applications in communications, sensing, and science, in which analogue signal transmission is preferred over today’s dominant digital transmission. In some of these applications, the advantage is in lower cost, while in others, it lies in superior performance. However, especially for longer analogue photonics links (up to 10 s of km), the performance is strongly limited by the impairments arising from using standard single-mode fibres (SSMF). Firstly, the three key metrics of analogue links (loss, noise figure, and dynamic range) tend to improve with received power, but this is limited by stimulated Brillouin scattering in SSMF. Further degradation is due to the chromatic dispersion of SSMF, which induces radio-frequency (RF) signal fading, increases even-order distortions, and causes phase-to-intensity-noise conversion. Further distortions still, are caused by the Kerr nonlinearity of SSMF. We propose to address all of these shortcomings by replacing SSMFs with hollow-core optical fibres, which have simultaneously six times lower chromatic dispersion and several orders of magnitude lower nonlinearity (Brillouin, Kerr). We demonstrate the advantages in this application using a 7.7 km long hollow-core fibre sample, significantly surpassing the performance of an SSMF link in virtually every metric, including 15 dB higher link gain and 6 dB lower noise figure.

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“…We measured the chromatic dispersion of our HCF and SSMF using the phase shift method 50 . The results are shown in Fig.…”

Section: Chromatic Dispersionmentioning

confidence: 99%

Low-loss microwave photonics links using hollow core fibres

et al. 2022

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“…By analyzing its dependence on the laser wavelength, the chromatic dispersion is calculated. [56] The chromatic dispersion increases linearly with wavelength over the measurement bandwidth. The slope that corresponds to S is then S = 70 fs km −1 nm −2 for SMF and 4 fs km −1 nm −2 for our HCF.…”

Section: Hcf and Smf Thermal Sensitivity Of Chromatic Dispersionmentioning

confidence: 99%

Stable Optical Frequency Comb Distribution Enabled by Hollow‐Core Fibers

Feng

Marra

Zhang

et al. 2022

Laser & Photonics Reviews

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Over the last two decades, optical frequency combs (OFCs) have enabled some of the most accurate measurements in physics. Distributing light from OFCs via optical fibers could make these high-accuracy measurement tools available more widely, from a few dedicated metrology laboratories to other laboratories and industry. However, the performance of distributed OFCs is strongly limited by impairments of standard single mode fiber (SMF), most notably its thermal sensitivity of chromatic dispersion, for which no compensation technique has been shown to date. To overcome this limitation, use of a new class of optical fiber is suggested here: a hollow core fiber (HCF), which offers more than an order of magnitude lesser such impairment. The measured OFC frequency stability of the optical mode and mode spacing reaches 1.8 × 10 −19 and 1.5 × 10 −17 at a few thousand seconds, respectively, after transmitting through 7.7 km of HCF. To the best of knowledge, this is the best ever performance for km-lengths of fiber-based OFC distribution. Besides, other HCF advantages over SMF in this application are discussed. Specifically, HCFs offer over an order of magnitude lower thermal sensitivity of propagation delay, several orders of magnitude lower optical nonlinearity, and almost ten times lower chromatic dispersion.

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“…Let us consider that the minimum change we can resolve is when the interference fringe moves by one half (e.g., from a minimum to a maximum). This corresponds to propagation time change of 2.5 fs (at 1555 nm), which is approximately 400 times more accurate than typically achievable in the time-of-flight measurement of the TCD [25] with 1-ps resolution. The TCD calculated using Eq.…”

mentioning

confidence: 90%

“…The TCD characterizes how optical signal propagation time τ through a fiber of unity length changes with temperature. To measure this with just the tens of meters of fiber length that we had available would require highly accurate propagation time measurement [25]. Alternatively, it can be quantified by measuring the light's phase thermal sensitivity S ϕ in an interferometer as we show below.…”

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Hollow-core fiber with stable propagation delay between −150°C and +60°C

Feng¹,

Sakr²,

Hayes³

et al. 2023

Opt. Lett.

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Optical fibers with a low thermal coefficient of delay (TCD) have been developed for frequency and timing transmission/distribution. However, their temperature sensitivity changes as a function of temperature and, to date, no study of such fibers has demonstrated improved performance over extended temperature ranges, especially at sub-zero temperatures. Here, we show that a hollow core fiber (HCF) with a thin acrylate coating can have a TCD within ±2.0 ps/km/°C over a broad temperature range from −150°C to +60°C. In addition, this thinly coated HCF can be fully insensitive to temperature around −134°C, making it of interest, e.g., for laser stabilization close to cryogenic temperatures.

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Polarization Effects on Thermally Stable Latency in Hollow-Core Photonic Bandgap Fibers

Cited by 5 publications

References 29 publications

Low-loss microwave photonics links using hollow core fibres

Low-loss microwave photonics links using hollow core fibres

Stable Optical Frequency Comb Distribution Enabled by Hollow‐Core Fibers

Hollow-core fiber with stable propagation delay between −150°C and +60°C

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