0.8
0.6
0.4
0.2
450500 550 600
Wavelength
(nm)
Intensity (a.u.) a) b)
650 700 Blue
Green
Red
R+G
R+B
R+G+B
0.0
0.2
0.4
0.6
0.8
1.0
G+B
0.0
0.0 0.2 0.4
x
y
0.6 0.8
460
500
540
560
580
600
620
640
R+G+B
D65
480
520
c) d) e) f)
g) h) i) j)
Top 20 technology
picks for 2015
showcase
wide scope of
photonics advances
JOHN WALLACE, Senior Editor
As in past years, this year’s set of 20 top technology picks
highlights the creativity and skill of the many scientists, engineers, technicians, and students—and, yes, managers and
directors, too—who continue to drive the field of photonics
forward at its breakneck pace. Possibly no other field can
boast that it thrives on contributions from experts in optics, physics, mechanics, materials sciences, electronics, and
chemistry (have I missed any?). In addition, no other field
is blessed with highly skilled opticians, CAD designers, lab
techs, and other adept people who advance the store of expe-rience-based knowledge that is the foundation of photonics.
You all have made possible not just this year’s Tech Review
Top 20 list, but the entire range of interconnected technologies that we call photonics.
1. Laser pixel for color displays.
How might one very small bit of semiconducting material produce laser light of any color desired, including white?
The question is a practical one, as an answer could lead to
bright and efficient pixels for color displays. One solution,
as determined by researchers at Arizona State University
(Tempe, AZ) and Tsinghua University (Beijing, China), is
to make the single pixel with a material composition that
varies across the pixel, allowing it to be pumped—at single or multiple points—to produce different colors (see
Fig. 1). The resulting chip, only 28.0 × 18.0 × 0.3 µm in size,
is composed of zinc cadmium sulfide selenide (ZnCdSSe) in
which the mix of Zn, Cd, S, and Se varies as a function of
location. While the prototype is optically pumped, the researchers aim to soon produce an electrically pumped version. (See “Multicolor Lasers: Semiconductor laser can produce many colors, including white,” LFW, September 2015;
http://bit.ly/1Pn0gmH.)
2. Lidar for everyone. While one way to sense the position of objects in a 3D scene is to imitate human stereo
vision by fusing information from two cameras to produce distance info, why not take a more straightforward
FIGURE 1. A multicolor laser made of segments containing
varying ratios of the elements in the semiconductor zinc cadmium
sulfide selenide can emit white light, single colors, or various
combinations as seen in (a), which shows lasing spectra for
various combinations. The chromaticity of the color combinations
in (a) are shown in the CIE color diagram in (b); the white-light
combination is very close to the CIE standard white illuminant
D65. (c) shows below-threshold pumping of the device, while
(d) through (j) show above-threshold pumping for the color
combinations shown in (a). (Courtesy of Cun-Zheng Ning)
