Ti:sapphire planar waveguide coherent broadband emitter

Summary form only given. In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical coherence tomography (OCT) for imaging applications in the biomedical field. A major challenge in the further development and applicability of OCT has been the improvement of both its spatial resolution and dynamic range. The longitudinal resolution is inversely proportional to the optical bandwidth of the light source. Broadband luminescence from transition-metal-ion doped materials, (e.g., Ti:sapphire) can significantly improve the longitudinal resolution compared to superluminescent diodes (/spl sim/30 nm FWHM), but the low brightness of its luminescence is insufficient for achieving a useful dynamic range in OCT. Femtosecond lasers have, therefore, been used as large-bandwidth high-brightness light sources, and subcellular imaging has recently been demonstrated in this way. However, current femtosecond light sources do not necessarily meet the requirements of compactness, ease of use, and low cost. We present a simple broadband light source based on a Ti:sapphire planar waveguide. It operates in a wavelength region near 800 nm, applicable to the investigation of biotissue and detectable with simple silicon diodes, with a bandwidth comparable to that of a femtosecond light source.