Akinetic swept-source optical coherence tomography based on a pulse-modulated active mode locking fiber laser for human retinal imaging

Abstract

Optical coherence tomography (OCT) is a noninvasive imaging modality that can provide high-resolution, cross-sectional images of tissues. Especially in retinal imaging, OCT has become one of the most valuable imaging tools for diagnosing eye diseases. Considering the scattering and absorption properties of the eye, the 1000-nm OCT system is preferred for retinal imaging. In this study, we describe the use of an akinetic swept-source OCT system based on a pulse-modulated active mode locking (AML) fiber laser at a 1080-nm wavelength for in-vivo human retinal imaging. The akinetic AML wavelength-swept fiber laser was constructed with polarization-maintaining fiber that has an average linewidth of 0.625 nm, a spectral bandwidth of 81.15 nm, and duty ratio of 90% without the buffering method. We successfully obtained in-vivo human retinal images using the proposed OCT system without the additional k-clock and the frequency shifter that provides a wide field of view of 43.1°. The main retina layers, such as the retinal pigment epithelium, can be distinguished from the OCT image with an axial resolution of 6.3 μm with this OCT system.

Phase stable swept-source optical coherence tomography with active mode-locking laser for contrast enhancements of retinal angiography

“…The sweep rate of the laser was set to 100 kHz over a wavelength range of approximately 100 nm, from 1030 to 1130 nm, with a duty cycle of 90%. (In our previous study, the swept-wavelength range was only 80 nm; widening it enhanced the axial resolution 15 .) The beam from the AML laser was divided into a sample arm and a reference arm using a 50:50 fiber coupler.…”

“…The configuration of the AML laser-based SS-OCT system used in the experiments is shown in Supplementary Figure S2 . The AML laser, which was upgraded from a previous study, was used as the light source in the system 15 . The sweep rate of the laser was set to 100 kHz over a wavelength range of approximately 100 nm, from 1030 to 1130 nm, with a duty cycle of 90%.…”

“…improved the imaging depth of the OCT system by applying a full-range technique using the high phase stability characteristics of the AML laser 14 . Further, in our previous study, we succeeded in increasing the imaging depth to 2.5 mm by improving the roll-off characteristics with an AML laser of 1080 nm via system optimization (applying high RF modulation frequency and pulse modulation) at a 100 kHz repetition swept rate for successful post-retinal imaging 15 . However, there are no known reports on the characteristics of swept-source AML lasers for enhancing the performance of the OCTA imaging system.…”

Phacoemulsification Induced Changes of Choroidal Thickness in Eyes with Age-Related Macular Degeneration

“…Cataract is a major reason of world blindness and visual impairment caused by the clouding of the natural eye lens [7]. The numbers of cataract blindness worldwide raised from 12.3 to 20 million during 20 years until 2010 [8].…”

“…Swept source-optical coherence tomography (SS-OCT) uses a 1050-nm laser beam as a light source and has high imaging speed [7,13]. This novel high-speed OCT system utilizes laser of longer wavelength range, which penetrates deeper into the choroidal tissue [14].…”