Search

Challenges and resolution approaches of fiber coupling to and from optical devices will be discussed. Particular emphasis will be paid to hermetic and ruggedized assemblies.

Packaging solutions developed for Luxmux's BeST SLED family of sources will be discussed along with their applications. In particular, a narrow linewidth ( 20mW output power from a compact fiber-coupled butterfly package will be presented.

This paper is a survey of recent achievements at the College of Optics and Photonics/CREOL at the University of Central Florida in the use of newly developed diffractive optical elements which are volume Bragg gratings recorded in a photo-thermo-refractive (PTR) glass. Three levels of semiconductor laser design are proposed to achieve high-power low-divergence output. The first level is coherent coupling of emitters by means of PTR Bragg gratings which provide excitation of only one common mode in a multichannel resonator. This type of phase locking automatically leads to a narrow spectral width of emission usually not exceeding a few tens of picometers. The second level is a change of the mechanism of transverse mode selection from spatial selection by apertures to angular selection by PTR Bragg gratings. This approach allows increasing of the aperture size without increasing the length and selecting of arbitrary mode but not necessarily a fundamental one. The third level is spectral beam combining by PTR Bragg gratings which re-direct radiation from several high-power fiber lasers to co-propagate in the same direction with diffraction limited divergence. This approach allows simplification of the thermal management because only passive devices with low absorption (a PTR volume Bragg gratings) are placed in the path of high power laser beam.

Five-channel spectral beam combining (SBC) using volume Bragg gratings (VBGs) in photo-thermo-refractive (PTR) glass with 0.5 nm spectral separation between channels and combined power >750 W has been recently reported. We report on improvements in this technique with the use of thermal control of VBGs that allows precise high-power alignment required for dense SBC with 0.25 nm spectral separation of channels. Experimental results of passive coherent beam combining (CBC) of fiber lasers using multiplexed VBGs are presented and analyzed. Methods for achieving 100 kW class systems using novel hybrid architectures that combine both coherent and spectral beam combining are discussed.

We introduce a novel technique of coherently locking fiber lasers using volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass as a passive multiplexer between channels. A two-channel coherently-locked Ybdoped fiber laser system with a narrow linewidth (~2.5 pm) and linear polarization (PER >20 dB) is demonstrated at a level of ~ 4 W (limited by pump). Scaling of this technique to coherently lock multiple (>2) fiber laser channels is discussed.

In this paper, we present the design of a 0.2 NA microscope objective operating across a 120nm broadband spectral range that requires only two doublets and an embedded liquid lens to achieve 3 μm invariant lateral resolution throughout a large 8 cubic millimeter imaging sample. Achieving invariant lateral resolution comes with some sacrifice in imaging speed, yet in the approach proposed, high speed in vivo imaging is maintained up to a resolution of 3 μm for a 2x2 mm sample size. Thus, in anticipation to ultimately aim for a resolution of 0.5 to 1 μm, we are investigating the possibility to further gain in resolution using super-resolution methods so both hardware solutions and image processing methods together can provide the best trade-off in overall resolution and speed of imaging. As a starting point to investigate super-resolution methods, we evaluate in this paper three well-known super-resolution algorithms used to reconstruct a high resolution image from down-sampled low resolution images of an African frog tadpole acquired en face using our OCM set-up. To establish ground truth necessary for assessment of the methods, low resolution images were simulated from a high resolution OCM image. The specification and design performance of the custom designed microscope will be presented as well as our first results of super-resolution imaging. The performance of each algorithm was analyzed and all performances compared using two different metrics. Early results indicate that super-resolution may play a significant role in the optimization of high invariant resolution OCM systems.

Broadband sources (BBSs) are commonly used in a wide range of applications in optical communication systems and biophotonics. They are particularly useful tools for Optical Coherence Tomography (OCT), which is a biomedical imaging technique that uses low-coherence light sources. In order to obtain high image quality, we have developed a novel, spectrally-flat S+C+L band source with > 120 nm bandwidth and more than 4 mW output power based on two cascaded semiconductor optical amplifiers (SOA) mixed with an Erbium-doped fiber (EDF) amplifier. Bandwidth and output power improvements are achieved by modifying the former configuration and mixing the EDF with the first SOA before amplification in the second SOA. This configuration results in bandwidth and output power enhancements of up to 146 nm and 8 mW, respectively. The source was then tested in an OCT system. It gives a 10 mm FWHM, low sidelobe OCT autocorrelation trace. Images and OCT autocorrelation traces were compared for the two aforementioned (which two; you mentioned one?) configurations. Images of miscellaneous samples made with the BBS show an image aspect and sharpness that is comparable with more expensive sources such as Ti:Sapphire lasers.