Broadband light source based on quantum-well superluminescent diodes for high-resolution optical coherence tomography

Emission of single quantum-well superluminescent diodes of two types in spectral ranges between 810 and 870 nm and between 860 and 970 nm is combined with the help of an original broadband fibre Y-coupler. Such a light source produces more than 5 mW of the cw output optical power and has a record small coherence length of about 5 μm. Its relative intensity noise does not exceed –135 dB Hz^-1 in the 100-kHz–10-MHz frequency range. The use of this source in an optical coherence tomography provides the recording of tomograms of biological objects in vivo with a spatial resolution of 2–3 μm.