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We demonstrate co-doped phosphor-in-glass (PiG) for high performance white light-emitting diodes (WLEDs) employing reduction of red/green phosphors interaction and antireflection coating (ARC). In this study, the novelties are a suitable selection of the 650-nm red and 540-nm green phosphor materials to reduce the mutual interaction between the emission of green phosphor and the absorption of red phosphor, evidenced by photoluminescence spectroscopy, and then an ARC on both sides of the PiG to reduce Fresnel reflection loss. Therefore, the PiG with high luminous efficiency of 63 lm/W, high color rendering index (CRI) of 96, and less amount of phosphor material are obtained. The overall luminous efficiency of the PiG-based WLED is improved by about 15% and the total amount of phosphors is reduced by about 58%. This proposed of co-doped PiG with excellent performance and less amount of phosphor material usage is essential to meet the economic requirement for high-quality WLEDs indoor lighting applications.

Gain enhancement of single-mode Cr-doped crystalline core fiber (SMCDCCF) with longer fiber length fabricated by online laser-heated pedestal growth (LHPG) technique is demonstrated. In comparison with the SMCDCCF fabricated without online growth, the online technique enables real-time monitoring and controlling small molten zone in the LHPG to achieve longer length with better uniformity and smaller core diameter of the SMCDCCFs. The SMCDCCF exhibits a length of 10.6 cm, a core diameter of 25 mu m, and a V-value of 2.40, which confirms the LP01 single-mode operation by the far-field pattern measurement. A 3.9-dB gross gain and a 1.9-dB net gain of the SMCDCCF at the wavelength of 1400 nm were obtained. The gross and net gains are the highest yet reported of the SMCDCCFs. Further development on higher gain of the SMCDCCF may be functioned the SMCDCCF as a broadband fiber amplifier for use in the next-generation fiber transmission systems.

An oriented-dependence-microlens (ODM) visual alignment and packaging for lasers coupling to polarization-maintaining-fibers (PMFs) is proposed and demonstrated. The ODM is fabricated by automatic grinding and accurate positioning techniques. The position accuracy of the grinding machine is ±1°, which is less than the aligned and fabricated angular tolerance of ±2° for the ODM necessary to achieve both high coupling of 80% and high polarized extinction ratio of 30 dB. This indicates that the ODM endface of the fast axis can be visually observed and then surface feature aligned to the axis of the laser polarization direction. A practical package of laser/PMF with compact size and a few components employing the ODM is also demonstrated. The proposed ODM with visually precise surface feature alignment to achieve both high coupling and polarization is beneficial for the application of laser/PMF modules for use in high-precision fiber optic gyroscopes and many high-performance and low-cost lightwave interconnections.

An experimental coupling mechanism is presented that demonstrates efficient coupling between a high-power 980-nm laser diode and a lensed fiber by employing mode (spot size and wavefront) matching in the near-field regime. The results show that the beam spot pattern of the lensed fiber of a horizontally elliptical shape is spot-size matched to the laser. The wavefront of the lensed fiber with a minor radius of curvature ranging from −9 to $10~\mu \text{m}$ exhibits a curve wave that is also phase matched to the laser. This indicates that the similarity in the mode patterns of both the spot size and the wavefront between lensed fiber and laser is responsible for mode-matched beam coupling, leading to a coupling efficiency of more than 80%. In contrast to the lensed fiber, the spot-size of the cleaved fiber is round, and the wavefront is a plane wave. The different mode distributions between the laser and the cleaved fiber lead to a mode mismatch, resulting in a coupling efficiency of lower than 40%. This experimental coupling mechanism investigation in the near-field regime provides useful information for practical micro-optic design with better mode matching to achieve efficient coupling from active to passive components for interconnect applications.

The fabrication of Ce-doped fibers (CeDFs) is demonstrated by drawing-tower method employing rod-in-tube technique. The fluorescence spectrum of CeDFs with a 16-μm core exhibited a 160-nm broadband emission with 1.45-μm axial resolution. This CeDF may be functioned as a high-resolution light source for optical coherence tomography applications.