Wideband Infrared Emission from Yb3+- and Nd3+-Doped Bi2O3–B2O3 Glass Phosphor for an Optical Coherence Tomography Light Source

We have investigated the spectroscopic properties of Bi 2 O 3 –B 2 O 3 glasses doped with Nd 3+ and Yb 3+ separately, and doubly doped with the same ions, in order to search for appropriate phosphors for an optical coherence tomography (OCT) light source. The effects of Yb 3+ and Nd 3+ co-doping and varying Yb 3+ concentration on the spectrum shape were studied to obtain an optimum line shape for OCT. We successfully obtained a Gaussian-like shape spectrum from 5.0Yb 2 O 3 –1.0Nd 2 O 3 –46.0Bi 2 O 3 –46.0B 2 O 3 (in nominal molar composition) with a full-width-at-half-maximum (FWHM) of 101 nm in the wavelength region around 1000 nm. This FWHM corresponds to a depth resolution of 4.5 µm, which is about twice that of conventional light emitting diodes (LEDs) and super luminescent diodes (SLDs). The Gaussian-like line shape is very important to suppress ghost images in OCT. These results indicate that a Yb 3+ , Nd 3+ co-doped Bi 2 O 3 –B 2 O 3 glass phosphor can indeed be applied as a new type of OCT light source.