Dispersion-flattened supercontinuum light source design at 1.0μm center wavelength for high resolution optical coherence tomography in ophthalmology

Optimal wavelength light sources are designed for medical imaging to overcome the effects of the dispersion of the sampling medium of biological tissues which contain about 60% water in normal tissues and 90% water in anatomic structures such as in the eye. Based on highly nonlinear photonic crystal fiber (HNL-PCF), two light sources are designed at 1.0μm center wavelength as the influences of the dispersion of the main component of biological tissues on the resolution of optical coherence tomography (OCT) can be eliminated. Using finite element method with a circular perfectly matched boundary layer, it is shown through simulations that the proposed HNL-PCFs offer efficient SC generation for such applications at 1.0μm. By propagating sech2 picoseconds optical pulses having 1.0 ps pulse width at a full width at half maximum through the proposed HNL-PCFs, output optical pulses are analyzed by the split-step Fourier method to obtain the spectral properties. Simulation results show that 270 m of the proposed HNL-PCF can produce highest 95 nm spectrum (10 dB bandwidth) or 62 nm spectrum (3 dB bandwidth). Therefore, the highest longitudinal resolutions in the depth direction for medical OCT imaging is found about 3.3μm (using 10 dB bandwidth) or 5.1μm (using 3 dB bandwidth), respectively, for biological tissues.

► Design of optimal wavelength broadband light sources for medical imaging at 1.0μm.
► Pure silica has been used as a background material for highly nonlinear photonic crystal fiber.
► 95 nm spectrum (10 dB bandwidth) has been observed using 270 m long PCF.
► The highest longitudinal resolution for biological tissues is found about 3.3μm at 1.0μm.