Laser-based wide-field coherent imaging methods suffer from low image contrast due to the speckle noise as well as poor lateral resolution using collimated illumination. To improve the image contrast and spatial resolution for label-free cell imaging applications, we propose a new dynamic speckle illumination scheme using perfect optical vortex (POV) beams that can provide finer speckles with more uniform distributions. The low spatial coherence from the POV speckle field has significantly improved the signal-to-noise ratio (SNR) and the image contrast, thus contributing to a high spatial resolution that matches the diffraction limit in our cell imaging experiments. Importantly, the depth-resolved imaging capability has been realized which has allowed us to visualize fine subcellular structures at different focal planes.
We demonstrate the first stable mode-locking from an Er3+ doped fluoride fibre laser cavity using various novel two-dimensional saturable absorber materials such as PtSe2 and MXene operating near 2.8 μm wavelength to the best of our knowledge. The linear cavity includes a high reflective chirped fibre Bragg grating to provide wavelength stability. The observed mode-locked pulse train has a 30 MHz repetition rate and an average power of 223 mW. Our results demonstrate the feasibility of using the novel two-dimensional nanomaterials such as PtSe2 and MXene into the fibre laser cavity for the application in mid-infrared wavelength regime.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.