Diode-pumped microlasers for display applications

Abstract

Laser displays have been investigated by engineers and scientists since shortly after the invention of the laser. The majority of these systems have been based on gas lasers or lamp-pumped solid-state lasers which are expensive, large in size, and require significant cooling systems. Due to these negative attributes, laser disp1ays have been limited to applications which are not sensitive to size or cost. Recent advances in compact, air-cooled, diode-pumped, solid-state, visible microlasers have enabled the development of portable laser displays. Lasers are under development for both "backlit" displays, where the lasers replace arc-lamps in an LCD/DMD projector, and "direct-write" displays, where the image is formed by directly modulating and scanning the laser beam. Compact, multi-watt RGB laser modules have been demonstrated for use as "light engines" in projection displays generating greater than 500 ANSI lumens. Advantages of microlaser-based displays include large color gamut, color accuracy, image uniformity, high resolution, large depth of focus, and low maintenance due to the long lifetime (> 10,000 hours) of the lasers. These advantages make them attractive for near term applications such as simulators, command and control centers, high end CAD workstation monitors, and longer term applications such as electronic cinema.

Laser-based displays: a review

“…Requirements of the laser source depend on the architecture of the display. For a flat panel backlit display, the laser beam M 2 parameter can be a few hundred times larger than that of a diffraction limited beam [3]. Display systems based on the flying spot approach are considered to be more suitable for mobile devices [4].…”

“…Direct modulation of the laser light with 2D modulators such as the DMD from Texas Instruments or LCDs has the advantage of requiring lower beam quality from the laser. As the étendue of these modulators is high, the beam can be many times diffraction limited with no adverse effects on efficiency [3]. Zheng et al demonstrated a projector based on this type of architecture.…”

“…For these types of backlit displays, the required laser beam quality (étendue) depends on the aperture size of the modulator and its angular acceptance [3]. As the étendue of the modulator is higher than the laser beam in most cases, inefficiencies do not arise.…”

Demonstration of a home projector based on RGB semiconductor lasers

“…In addition, the laser source has a good reliability and a long life time. Many efforts were made to take full advantage of lasers in the laser projection systems presented in recent years [4,[5][6][7][8][9][10][11][12]. However, the bulky size of traditional high-power laser sources and the speckle noise caused by the coherence of the laser light are still significant obstacles for the further improvement of the laser projection and have not been completely solved yet [4,13,[14][15][16][17][18].…”

“…However, the bulky size of traditional high-power laser sources and the speckle noise caused by the coherence of the laser light are still significant obstacles for the further improvement of the laser projection and have not been completely solved yet [4,13,[14][15][16][17][18]. Laser array source modules based on RGB direct-emission semiconductor laser diode (LD) are compact and can provide high optical power, although the single output power of current semiconductor LDs is low [8][9][10][11][12]. In addition, the laser array consisting of lots of LDs is of great benefit to speckle suppression.…”