| Autor: |
Szwaj M; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK.; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.; School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK., Davidson IA; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Johnson PB; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.; School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK., Jasion G; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Jung Y; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Sandoghchi SR; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Herdzik KP; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK.; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.; School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK., Bourdakos KN; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.; School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK., Wheeler NV; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Mulvad HC; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Richardson DJ; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Poletti F; Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK., Mahajan S; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.; School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK. |
| Abstrakt: |
Label-free and multiphoton micro-endoscopy can transform clinical histopathology by providing an in situ tool for diagnostic imaging and surgical treatment in diseases such as cancer. Key to a multiphoton imaging-based micro-endoscopic device is the optical fiber, for distortion-free and efficient delivery of ultra-short laser pulses to the sample and effective signal collection. In this work, we study a new hollow-core (air-filled) double-clad anti-resonant fiber (DC-ARF) as a high-performance candidate for multiphoton micro-endoscopy. We compare the fiber characteristics of the DC-ARF with a single-clad anti-resonant fiber (SC-ARF) and a solid core fiber (SCF). In this work, while the DC-ARF and the SC-ARF enable low-loss (<0.2 dBm -1 ), close to dispersion-free excitation pulse delivery (<10% pulse width increase at 900 nm per 1 m fiber) without any induced non-linearities, the SCF resulted in spectral broadening and pulse-stretching (>2000% of pulse width increase at 900 nm per 1 m fiber). An ideal optical fiber endoscope needs to be several meters long and should enable both excitation and collection through the fiber. Therefore, we performed multiphoton imaging on endoscopy-compatible 1 m and 3 m lengths of fiber in the back-scattered geometry, wherein the signals were collected either directly (non-descanned detection) or through the fiber (descanned detection). Second harmonic images were collected from barium titanate crystals as well as from biological samples (mouse tail tendon). In non-descanned detection conditions, the ARFs outperformed the SCF by up to 10 times in terms of signal-to-noise ratio of images. Significantly, only the DC-ARF, due to its high numerical aperture (NA) of 0.45 and wide-collection bandwidth (>1 µm), could provide images in the de-scanned detection configuration desirable for endoscopy. Thus, our systematic characterization and comparison of different optical fibers under different image collection configurations, confirms and establishes the utility of DC-ARFs for high-performing label-free multiphoton imaging-based micro-endoscopy. |
