Nonlinear self-trapping and guiding of light at different wavelengths with sheep blood.

We demonstrate the formation of waveguides, a few centimeters long, in colloidal suspensions of sheep red blood cells for a wide range of wavelengths due to nonlinear self-trapping and self-guiding of a laser beam. The near infrared (NIR) light experiences a weaker nonlinear self-action and thus requires much higher power to obtain self-trapping as compared to visible light. To examine the waveguiding of light at different wavelengths, we utilize a pump-probe-type setting for beam coupling: a pump beam at a 532 nm wavelength is used to create a waveguide first, and then a probe beam with various wavelengths is sent through the waveguide channel. Effective guidance for both visible and NIR wavelengths is observed through such otherwise highly scattering bio-soft-matter.