Advances in broad bandwidth light sources for ultrahigh resolution optical coherence tomography

Abstract

Novel ultra-broad bandwidth light sources enabling unprecedented sub-2 microm axial resolution over the 400 nm-1700 nm wavelength range have been developed and evaluated with respect to their feasibility for clinical ultrahigh resolution optical coherence tomography (UHR OCT) applications. The state-of-the-art light sources described here include a compact Kerr lens mode locked Ti:sapphire laser (lambdaC = 785 nm, delta lambda = 260 nm, P(out) = 50 mW) and different nonlinear fibre-based light sources with spectral bandwidths (at full width at half maximum) up to 350 nm at lambdaC = 1130 nm and 470 nm at lambdaC = 1375 nm. In vitro UHR OCT imaging is demonstrated at multiple wavelengths in human cancer cells, animal ganglion cells as well as in neuropathologic and ophthalmic biopsies in order to compare and optimize UHR OCT image contrast, resolution and penetration depth.

Simultaneous quantum dash-well emission in a chirped dash-in-well superluminescent diode with spectral bandwidth >700 nm

“…To date, most commercial ultrabroadband sources are based on nonlinear optical transformations of ultrashort laser pulses and photonic crystal fiber based approaches, which often involve an expensive and bulky high-power laser as pump source, and utilize complex filtering systems [3,4]. For many practical applications, a compact, efficient, and cost-effective broadband device is preferred.…”

Gallium nitride light sources for optical coherence tomography

“…Since OCT was first reported in 1991 by Huang et al, [17] axial resolution and imaging speed have both been increased, with the former limited by the device central wavelength and bandwidth [18]. In lieu of broad bandwidth GaN SLEDs and in an attempt to access shorter wavelengths, super-continuum lasers [19] and non-linear fibre-based light sources [20] have been demonstrated. This showed in vivo imaging of the human skin using OCT is possible at ~400 nm and ultraviolet light is able to propagate to the dermal layer [21].…”

Efficient generation of 509 nm light by sum-frequency mixing between two tapered diode lasers

“…This wide emission band enables the generation of very short pulses and Ti:sapphire lasers are therefore preferred for biophotonics imaging [5], spectroscopy [6] or materials processing [7]. Ti:sapphire has its absorption peak located around 490 nm.…”