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Rodrigo Amezcua-Correa

Publications and source records attributed to Rodrigo Amezcua-Correa.

49 records · Page 3Linked to original sources
arXiv2020

Impact of cladding elements on the loss performance of hollow-core anti-resonant fibers

Understanding the impact of the cladding tube structure on the overall guiding performance is crucial for designing single-mode, wide-band, and ultra low-loss nested hollow-core anti-resonant fiber (HC-ARF). Here we thoroughly investigate on how the propagation loss is affected by the nested elements when their geometry is realistic (i.e., non-ideal). Interestingly, it was found that the size rather than the shape of the nested elements, have a dominant role in the final loss performance of the HC-ARFs. We identify a unique 'V-shape' pattern for suppression of higher-order modes loss by optimizing free design parameters of HC-ARF. We find that a 5-tube nested HC-ARF has wider transmission window and better single-mode operation than 6-tube HC-ARF. We show that the propagation loss can be significantly improved by using anisotropic nested anti-resonant tubes elongated in the radial direction. Our simulations indicate that with this novel fiber design, a propagation loss as low as 0.11 dB/km at 1.55 $μ$m can be achieved. Our results provide design insights towards fully exploiting single-mode, wide-band, and ultra low-loss HC-ARF. In addition, the extraordinary optical properties of the proposed fiber can be beneficial for several applications such as future optical communication system, high energy light transport, extreme non-nonlinear optics and beyond.

physics.optics↗
arXiv2020

Multi-wavelength high energy gas-filled fiber Raman laser spanning from 1.53 um to 2.4 um

In this work, we present a high pulse energy multi-wavelength Raman laser spanning from 1.53 um up to 2.4 um by employing the cascaded rotational stimulated Raman scattering (SRS) effect in a 5-m hydrogen (H2) -filled nested anti-resonant fiber (NARF), pumped by a linearly polarized Er/Yb fiber laser with a peak power of ~13 kW and pulse duration of ~7 ns in the C-band. The developed Raman laser has distinct lines at 1683 nm, 1868 nm, 2100 nm, and 2400 nm, with pulse energies as high as 18.25 uJ, 14.4 uJ, 14.1 uJ, and 8.2 uJ, respectively. We demonstrate how the energy in the Raman lines can be controlled by tuning the H2 pressure from 1 bar to 20 bar

physics.optics↗
arXiv2020

Mode-dependent Loss and Gain Estimation in SDM Transmission Based on MMSE Equalizers

The capacity in space division multiplexing (SDM) systems with coupled channels is fundamentally limited by mode-dependent loss (MDL) and mode-dependent gain (MDG) generated in components and amplifiers. In these systems, MDL/MDG must be accurately estimated for performance analysis and troubleshooting. Most recent demonstrations of SDM with coupled channels perform MDL/MDG estimation by digital signal processing (DSP) techniques based on the coefficients of multiple-input multiple-output (MIMO) adaptive equalizers. Although these methods provide a valid indication of the order of magnitude of the accumulated MDL/MDG over the link, MIMO equalizers are usually updated according to the minimum mean square error (MMSE) criterion, which is known to depend on the channel signal-to-noise ratio (SNR). Therefore, MDL/MDG estimation techniques based on the adaptive filter coefficients are also impaired by noise. In this paper, we model analytically the influence of the SNR on DSP-based MDL/MDG estimation, and show that the technique is prone to errors. Based on the transfer function of MIMO MMSE equalizers, and assuming a known SNR, we calculate a correction factor that improves the estimation process in moderate levels of MDL/MDG and SNR. The correction factor is validated by simulation of a 6-mode long-haul transmission link, and experimentally using a 3-mode transmission link. The results confirm the limitations of the standard estimation method in scenarios of high additive noise and MDL/MDG, and indicate the correction factor as a possible solution in practical SDM scenarios.

eess.SP↗
arXiv2019

Mode-Multiplexed Full-Field Reconstruction Using Direct and Phase Retrieval Detection

We realize mode-multiplexed full-field reconstruction over six spatial and polarization modes after 30-km multimode fiber transmission using intensity-only measurements without any optical carrier or local oscillator at the receiver or transmitter. The receiver's capabilities to cope with modal dispersion and mode dependent loss are experimentally demonstrated.

eess.SP↗
arXiv2019

Noise and spectral stability of deep-UV gas-filled fiber-based supercontinuum sources driven by ultrafast mid-IR pulses

Deep-UV (DUV) supercontinuum (SC) sources based on gas-filled hollow-core fibers constitute perhaps the most viable solution towards ultrafast, compact, and tunable lasers in the UV spectral region. Noise and spectral stability of such broadband sources are key parameters that define their true potential and suitability towards real-world applications. In order to investigate the spectral stability and noise levels in these fiber-based DUV sources, we generate an SC spectrum that extends from 180 nm (through phase-matched dispersive waves - DWs) to 4 μm by pumping an argon-filled hollow-core anti-resonant fiber at a wavelength of 2.45 μm. We characterize the long-term stability of the source over several days and the pulse-to-pulse relative intensity (RIN) noise of the strongest DW at 275 nm. The results indicate no sign of spectral degradation over 110 hours, but the RIN of the DW pulses at 275 nm is found to be as high as 33.3%. Numerical simulations were carried out to investigate the spectral distribution of the RIN and the results confirm the experimental measurements and that the poor noise performance is due to the RIN of the pump laser, which was hitherto not considered in numerical modelling of these sources. The results presented herein provide an important step towards an understanding of the noise mechanism underlying such complex light-gas nonlinear interactions and demonstrate the need for pump laser stabilization.

physics.optics↗
arXiv2019

Observation of twist-induced geometric phases and inhibition of optical tunneling via Aharonov-Bohm effects

Geometric phases appear ubiquitously in many and diverse areas of physical sciences, ranging from classical and molecular dynamics to quantum mechanics and solid-state physics. In the realm of optics, similar phenomena are known to emerge in the form of a Pancharatnam-Berry phase whenever the polarization state traces a closed contour on the Poincare sphere. While this class of geometric phases has been extensively investigated in both free-space and guided wave systems, the observation of similar effects in photon-tunneling arrangements has so far remained largely unexplored. Here, for the first time, we experimentally demonstrate that the tunneling or coupling process in a twisted multi-core fiber system can display a chiral geometric phase accumulation-analogous to that of the Aharonov-Bohm effect resulting from the presence of a nonzero magnetic flux. In our experiments, the tunneling geometric phase is manifested through the interference of the corresponding supermodes. In this system, and for specific values of the twist rate, the tunneling between opposite cores ceases, thus signifying an Aharonov-Bohm suppression of tunneling. Our work provides the first observation of this intriguing effect in an optical setting.

physics.optics↗
arXiv2018

Deep-UV to mid-IR supercontinuum generation driven by mid-IR ultrashort pulses in a gas-filled fiber

Supercontinuum (SC) generation based on ultrashort pulse compression constitutes one of the most promising technologies towards an ultra-wide bandwidth, high-brightness and spatially coherent light sources for applications such as spectroscopy and microscopy. Here, multi-octave SC generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the mid-infrared (mid-IR). A measured average output power of 5 mW was obtained by pumping at the center wavelength of the first anti-resonance transmission window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~7-8 μJ. The mechanism behind the extreme spectral broadening relies upon intense soliton-plasma nonlinear dynamics which leads to efficient soliton self-compression and phase-matched dispersive wave (DW) emission in the DUV region. The strongest DW is observed at 275 nm having an estimated pulse energy of 1.42 μJ, corresponding to 28.4 % of the total output energy. Furthermore, the effect of changing the pump pulse energy and gas pressure on the nonlinear dynamics and their direct impact on SC generation was investigated. The current work paves a new way towards novel investigations of gas-based ultrafast nonlinear optics in the emerging mid-IR spectral regime.

physics.optics↗
arXiv2016

A systematic approach for designing zero-DGD coupled multi-core optical fibers

An analytical method is presented for designing N-coupled multi-core fibers with zero differential group delay. This approach effectively reduces the problem to a system of N-1 algebraic equations involving the associated coupling coefficients and propagation constants as obtained from coupled mode theory. Once the parameters of one of the cores are specified, the roots of the resulting N-1 equations can then be used to determine the characteristics of the remaining waveguide elements. Using this technique, a number of pertinent geometrical configurations are investigated in order to minimize intermodal dispersion.

physics.optics↗