**5.4 CL-827-R45-XT**

Conventionally, phosphors are mixed with organic or silicone resin to form a phosphor film; however, such composition will ultimately harden and leads to discoloration. Moreover, these components are sensitive to heat and water, reducing the device's lifespan and making them unsuitable for outdoor applications. Phosphor on glass is increasingly replacing conventional color convertors, especially for outdoor high power and high brightness applications. The fabrication process of phosphor on glass is simple as the mixture of phosphors is coated on a transparent glass and can be sintered at <sup>0</sup> 800 C. The characteristic of generated white light can also be easily controlled by changing the phosphor concentration ratio and thickness. This section studied the properties of generated white light from commercially available phosphor coated on glass CL-827-R45-XT. The Photography of CL-827- R45-XT is shown in **Figure 10**.

The experimental setup to measure emission spectra of generated white light at different bias currents is shown in **Figure 11(a)**. The emission spectra of the generated white light after the blue LD exciting the phosphor coated on glass at room temperature, under bias currents of 220 mA, 240 mA, 280 mA, 320 mA, 360 mA, are shown in **Figure 11(b)**. The peak emission wavelength of blue light is at 439 nm, while that of the yellow light is at 577 nm. It can be seen that the peak emission wavelength of generated light is not changed considerably with increasing

**Figure 10.** *Photography of CL-827-R45-XT.*

#### **Figure 11.**

*(a) Experimental setup to measure emission spectra. (b) The emission spectra of the generated light at different bias currents.*

**Figure 12**

**(a) The photography of generated white light spot.** *(b) Chromaticity coordinates diagram of the generated white light at 360 mA.*

bias current, which indicates that the phosphor-coated on glass is suitable to be used with the high injection bias current.

The photography of the generated white light spot is shown in **Figure 12(a)**. The CIE coordinate of the white light source at 360 mA on the CIE 1931 chromaticity diagram is shown in **Figure 12(b)**. At 360 mA, white light has a CCT of 3786, CRI of 87.9, and the CIE coordinates fall at (0.3556, 0.3026), which is very close to the standard neutral white light (0.33, 0.33).
