High-resolution wavefront shaping with a photonic crystal fiber for multimode fiber imaging

Abstract

We demonstrate that a high-numerical-aperture photonic crystal fiber allows lensless focusing at an unparalleled resolution by complex wavefront shaping. This paves the way toward high-resolution imaging exceeding the capabilities of imaging with multi-core single-mode optical fibers. We analyze the beam waist and power in the focal spot on the fiber output using different types of fibers and different wavefront shaping approaches. We show that the complex wavefront shaping technique, together with a properly designed multimode photonic crystal fiber, enables us to create a tightly focused spot on the desired position on the fiber output facet with a subwavelength beam waist.

Ultrathin endoscopes based on multicore fibers and adaptive optics: a status review and perspectives

“…While the majority of the initial reports of lensless endoscopes used MMF as the waveguide, [33][34][35][36][37][38][39][40][41][42][43] MCFs can also be used, as can any other waveguide with spatial degrees of freedom. In this section, we will describe the merits of the MCFs that we have designed during our work on lensless endoscopes; in effect, these MCFs have been designed to enhance these merits, which, consequently, may not hold for generic MCFs.…”

Group velocity distribution and short-pulse dispersion in a disordered transverse Anderson localization optical waveguide

“…What sets a TALOF apart from a conventional MMF is that its guided modes are spatially localized due to the transverse disorder, while the guided modes in a conventional MMF typically cover all or a large portion of the guiding region [37][38][39]. The modal characteristics of MMFs are generally responsible for their performance for the desired functionality [40][41][42][43][44]; e.g., the mean localization radius of the modes in an imaging TALOF determines the average point spread function (PSF) across the tip of the fiber, where a stronger localization leads to a narrower PSF and a higher resolution image transport [22]. Similarly, the standard deviation in the localization radius of the modes determines the uniformity of the image transport * mafi@unm.edu across the fiber.…”

Excitation of higher-order modes in optofluidic photonic crystal fiber

“…The radii of these rings correspond to the input angle θ ext = θ core × n w at which the mode is most efficiently excited (see Fig 6f); Eqn. (5) can be used to estimate the corresponding mode index. Optimum coupling into the LP 11 , LP 21 , LP 12 , and the LP 33 modes was achieved for θ ext values of (1.1 ± 0.2) • , (1.7 ± 0.2) • , (2.6 ± 0.2) • , and (4.1 ± 0.2) • respectively, which were determined by finding minima of the FP radial distribution profiles.…”

“…The controlled excitation of higher-order fiber modes has become an increasingly active area in photonics research with a range of interdisciplinary applications. For example, spatial light modulator (SLM)-based wavefront shaping techniques [1] have enabled the controlled excitation of coherent mode superpositions in multimode fibers [2], with novel applications in lensless endoscopic imaging [3,4,5] and fiber-based optical trapping [6]. In fiber communication systems, mode-division multiplexing has been used to improve data transfer rates [7,8,9,10].…”