Watt‐Class Green (530 nm) and Blue (465 nm) Laser Diodes

Abstract

In this research, watt-class green and blue laser diodes, which are fabricated on free-standing semipolar 20 21g f GaN and conventional c-plane GaN substrates, respectively are developed. Although several research groups have recently developed green laser diodes on semipolar GaN substrates, which have weaker piezoelectric fields and higher indium homogeneity in InGaN active regions compared to c-plane GaN, watt-level output power has yet to be achieved. By utilizing the 20 21g f plane, the first watt-class green lasers at 530 nm is successfully fabricated, and achieve maximum output powers in excess of 2 W, which to the best of our knowledge is the highest value reported for any GaN-based green laser diode. A wall-plug efficiency of 17.5% is realized at a current of 1.2 A under continuous-wave operation, which corresponds to an optical output of approximately 1 W and is the highest value reported to date. In addition, high-power and high-efficiency blue laser diodes at 465 nm are successfully fabricated on conventional c-plane GaN substrates. The output power and wall-plug efficiency are 5.2 W and 37.0%, respectively, at a current of 3.0 A under continuous-wave operation. These laser diodes are promising light sources meeting the ITU-R Recommendation BT.2020 for future laser display applications.

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

“…A perfect 3D light diffuser exhibits angle independent (isotropic) emission over the complete angular range, so that the light is uniformly emitted in all directions. [18][19][20]. In both cases, the photodiode is pivoted, while the sample and the LD are stationary.…”

“…Especially the latter is a strict requirement for LD-based lighting, that is not met by today's commercially available diffuser systems (Supplementary Note 1 and Supplementary Table 1). Even though the current state of LD technology -with laser efficiencies < 20% for green 19 and < 40% for blue 2,19 -is still limiting the application of LD-based lighting systems, fast progress in the development of more efficient laser diodes is expected in the near future [2][3][4]8 . Therefore, the development of new optical components, such as the Aero-BN discussed here, is a necessity, indicating a way to unlock the full potential of LDs for high-brightness illumination, such as needed in projector technology, automotive headlights, large room illumination, and sports lighting.…”

A Decade of Nonpolar and Semipolar III-Nitrides: A Review of Successes and Challenges

“…For instance, semipolar green LEDs show efficiencies approaching those of c ‐plane LEDs (as shown in Figure ) and low threshold LDs in the green have been demonstrated (as shown in Figure ). In addition, the highest power green lasers ever reported on any orientation were recently shown using semipolar . Hence, although the nonpolar orientations have not been very successful in the green, some of the semipolar planes have shown excellent performances in the green region.…”

Hydrogen Can Passivate Carbon Impurities in Mg-Doped GaN

“…GaN-based third-generation semiconductor materials and their alloys have attracted great attention [1] due to their broad applications including light-emitting diodes (LEDs) [2][3][4] and laser diodes (LDs) [5][6][7]. Although GaN-based photonic devices are widely commercialized, the relatively low hole concentration and high resistivity of p-type GaN still significantly limit the performance of such devices [8,9].…”