Search

An essential factor of the particle number is exploited for the phosphor excitation in phosphor-converted white LEDs. The particle number can clearly reveal the dependence of the light output flux and the correlated color temperature upon the conventional parameters, thickness, and concentration of the phosphors in a simpler way. In addition, we also find that there might exist an optimal particle number for the maximal luminous light output. An empirical function is then proposed for successfully modeling the relation between the output light and the particle number.

Fiber Mach–Zehnder interferometers (F-MZI) are widely used for fiber Bragg grating (FBG) sensor interrogation purpose due to their advantages in terms of wide bandwidth, high resolution, and tunable sensitivity. They are appropriate for dynamic strain measurement applications in the areas of vibration analysis, hydrophones, and acoustic emission studies. The interferometer converts the Bragg wavelength shift of an FBG sensor into a corresponding phase shift which is finally recorded as intensity variations at the output. Power fluctuations of the light source as well as disturbances in the light guiding path and/or dependence of light source intensity on wavelength introduce fictitious output intensity variations resulting into significant measurement errors. We propose and experimentally demonstrate a dual-channel F-MZI approach that eliminates the light intensity disturbance noise. Furthermore, the proposed method also improves the demodulated signal quality by a factor of $\sim 3$ dB. [ABSTRACT FROM PUBLISHER]

White light LEDs are playing a more and more important role in display in various structures. Here, a new modeling algorithm is proposed for use in phosphor-converted white light-emitting diodes (pcW-LEDs); the algorithm can be used to accurately simulate color appearances, potentially enabling optical designers to remove yellowish/bluish spots in LED lighting. The proposed modeling method was applied to simulate a pcW-LED without an encapsulation lens, and subsequently, a pcW-LED with a hemispherical lens. Both simulations accurately predicted the blue and yellow light distribution. The model was further verified by applying a total internal reflector lens to the pcW-LED. In the midfield region, the blue and yellow light distribution exhibited large variations as the observation distance changed; this varying light pattern for both the blue and yellow lights can be accurately predicted using the proposed model. The developed optical model should facilitate designing a pcW-LED that features high-quality illumination and increased color uniformity. [ABSTRACT FROM AUTHOR]

A new scheme for a flexible modulation and bit rate independent, polarization-insensitive optical wavelength converter (WC) based on four-wave mixing in a highly nonlinear fiber is demonstrated and characterized for different modulation formats and data rates. Its robustness is demonstrated in a data transmission experiment in which the WC is incorporated at the mid-point of a transmission line based on installed fiber. In addition, an optical feedback system designed to prevent slow polarization drift of the pumps, and consequently, to ensure the long-term stability of the system is implemented and characterized. The WC is tested with the feedback system in place enabling turn-key operation. [ABSTRACT FROM PUBLISHER]

In the paper, an optical design for a standard light source is proposed and demonstrated to perform high stability, high angular CCT (correlated color temperature) uniformity, and adjustable light pattern from a Lambertian-like pattern to a narrow light pattern with a full-width at half-maximum (FWHM) angle of 60 °. The optical module contains a color-mixing cylinder, a diffuser, and an absorbed cylinder. The simulation well predicts the corresponding measurements and the angular CCT deviation can be kept a certain low level, which is much lower than a general phosphor converted white LED. In addition, we apply a pcW-LED of CREE XML as the light source to the optical module to show the general adoptability of the optical module. The measurement shows that the similar behavior, with adjustable light pattern from 120 ° to 60 °. In addition, the angular correlated color temperature deviation (ACCTD) is always kept an extremely low level. [ABSTRACT FROM PUBLISHER]