Tuan Le

Compact, low-cost Ti:Al2O3 laser for in vivo ultrahigh-resolution optical coherence tomography

A compact, low-cost, prismless Ti:Al2O3 laser with 176-nm bandwidth (FWHM) and 20-mW output power was developed. Ultrahigh-resolution ophthalmic optical coherence tomography (OCT) ex vivo imaging in an animal model with approximately 1.2-microm axial resolution and in vivo imaging in patients with macular pathologies with approximately 3-microm axial resolution were demonstrated. Owing to the pump laser, this light source significantly reduces the cost of broadband OCT systems. Furthermore, the source has great potential for clinical application of spectroscopic and ultrahigh-resolution OCT because of its small footprint (500 mm x 180 mm including the pump laser), user friendliness, stability, and reproducibility.

A higher-order-mode fiber delivery for Ti:Sapphire femtosecond lasers

We report the first higher-order-mode fiber with anomalous dispersion at 800nm and demonstrate its potential in femtosecond pulse delivery for Ti:Sapphire femtosecond lasers. We obtain 125fs pulses after propagating a distance of 3.6 meters in solid-silica fiber. The pulses could be further compressed in a quartz rod to nearly chirp-free 110fs pulses. Femtosecond pulse delivery is achieved by launching the laser output directly into the delivery fiber without any pre-chirping of the input pulse. The demonstrated pulse delivery scheme suggests scaling to >20meters for pulse delivery in harsh environments not suited for oscillator operation or in applications that require long distance flexibility.

Multimodal imaging fiber probe for biomedical applications (Conference Presentation)

Multimodal label-free optical microscopy for in vivo and in situ imaging of human tissue represents a challenge especially when nonlinear optical techniques are used. One possible solution to address this challenge is the use of specific hand-held and endomicroscopy probes, based on optical fibers, capable to image at the same time the chemical composition and the morphological structure of the tissues. Nonlinear optical imaging techniques, including TPEF, SHG, spectral focusing CARS, combined with spectral domain OCT are capable to give functional, molecular and morphological information. Since nonlinear optical microscopy and SD-OCT require ultrashort pulses to efficiently image the targeted sample, the development of such probes requires specific attention to high peak power and ultrashort pulse delivery at the focal plane. Different optical fiber technologies for femtosecond pulse delivery are experimentally investigated in order to suggest an optical fiber that fulfill at the same time the requirements for above mentioned imaging modalities. We investigated three different approaches that are normally considered for ultrashort pulse delivery: large-mode area (LMA) fiber, hollow-core photonic bandgap fiber and kagome hollow-core fiber from GLOphotonics. We tested this three fibers on our label-free multimodal imaging platform which is capable to simultaneously acquire TPEF, SHG, spectral focusing CARS and SD-OCT. From our investigation, we identify the fiber which better satisfy the requirements of all the above mentioned imaging modalities in terms of dispersion profile and transmission of high energy pulses. Imaging capabilities are shown on a biological tissue of interest.

Dispersive mirror compressors for few-cycle laser pulses

The implementation of multilayer optics for the compression and delivery of few-cycle femtosecond pulses will be discussed in the case of several cutting-edge applications.

Tabletop generation of carrier envelope phase stabilized multi-mJ few-cycle pulses

A compact system for the generation of few-cycle multi-mJ carrier envelope phase (CEP) stabilized pulses is presented. The output 5.4 fs, 1.9 mJ pulses have CEP noise of only 190 mrad rms over seven hours.

Ophthalmic ultrahigh resolution OCT using a portable low cost Ti:Al 2 O 3 laser

A compact, low cost prismless Titanium:sapphire laser with 154nm bandwidth and 20mW output power was developed and ultrahigh resolution OCT ex vivo imaging in an animal model with sub-2μm and in vivo imaging in patients with 3μm axial resolution is demonstrated. This light source not only significantly reduces costs for broadband OCT light sources, but has also great potential for clinical OCT applications due to its small footprint (500x200mm including pump laser), user-friendliness and power stability.