Laser-Based Lighting: Experimental Analysis and Perspectives

Abstract

This paper presents an extensive analysis of the operating principles, theoretical background, advantages and limitations of laser-based lighting systems. In the first part of the paper we discuss the main advantages and issues of laser-based lighting, and present a comparison with conventional LED-lighting technology. In the second part of the paper, we present original experimental data on the stability and reliability of phosphor layers for laser lighting, based on high light-intensity and high-temperature degradation tests. In the third part of the paper (for the first time) we present a detailed comparison between three different solutions for laser lighting, based on (i) transmissive phosphor layers; (ii) a reflective/angled phosphor layer; and (iii) a parabolic reflector, by discussing the advantages and drawbacks of each approach. The results presented within this paper can be used as a guideline for the development of advanced lighting systems based on laser diodes.

A Thermally Robust La3Si6N11:Ce‐in‐Glass Film for High‐Brightness Blue‐Laser‐Driven Solid State Lighting

“…On the other hand, the strong green emission at ≈530 nm matches well with the color filter, which makes LSN:Ce more competitive than YAG:Ce to achieve a larger color gamut. Third, it has a shorter decay time (≈40 ns) than YAG:Ce (≈60 ns), ensuring the less non‐thermal optical saturation under the high‐density laser excitation . These encouraging properties promise LSN:Ce to be particularly suitable for laser lighting and displays.…”

Conversionless efficient and broadband laser light diffusers for high brightness illumination applications

“…However, the performance of such systems is strongly limited by the properties of the phosphor. The efficiency of state-of-the-art light emitting phosphors, such as doped yttrium-aluminum-garnet, is mainly determined by two types of energy losses, the stokes shift (~80% efficiency) and the photoluminescence quantum yield (~90%) 10 . Both these loss mechanisms scale with temperature 10 (e.g., as a result of illumination) and therefore phosphor luminescence suffers from saturation 10 , aging 11 , and thermal quenching 10 , limiting the irradiance tõ 5 kW cm −2 and thus the overall light output.…”

“…The efficiency of state-of-the-art light emitting phosphors, such as doped yttrium-aluminum-garnet, is mainly determined by two types of energy losses, the stokes shift (~80% efficiency) and the photoluminescence quantum yield (~90%) 10 . Both these loss mechanisms scale with temperature 10 (e.g., as a result of illumination) and therefore phosphor luminescence suffers from saturation 10 , aging 11 , and thermal quenching 10 , limiting the irradiance tõ 5 kW cm −2 and thus the overall light output. Even though new concepts such as glass encapsulation 12,13 , phosphor monoliths 14 , or composite ceramic phosphors [15][16][17] can increase the irradiance level up to~10-20 kW cm −2 , the true potential of lasers for highbrightness lighting applications, with possible light outputs of several MW cm −2 , still remains unemployed.…”

High Power Laser‐Driven Ce3+‐Doped Yttrium Aluminum Garnet Phosphor Incorporated Sapphire Disc for Outstanding White Light Conversion Efficiency

“…In comparison with blue LEDs, blue laser diodes can be a better alternative source to resolve the issues created by the LEDs. Thus, the blue laser diode could be used as a next light source that would revolutionize the lighting technology especially in automotive lighting applications . In addition, the color stability of laser can be maintained because of the characteristic behavior of the output power.…”

“…This composite disc is placed in front of the blue laser diodes for increasing the luminous efficacy and power intensity, thereby enhancing the life and performance of white light. However, the use of YAG:Ce composite disc with blue laser diodes for white light generation to be used widely in displays, lamps, light fidelity, and automotive lighting, which has yet to be investigated in details . There are several efforts that have been employed for the synthesis of YAG:Ce phosphor powder using different techniques such as co‐precipitation, sol–gel, combustion, and spray pyrolysis to obtain high crystallinity, large luminous power, and small particle size .…”