High-efficiency VCSEL arrays for illumination and sensing in consumer applications Jean-Francois Seurin, Delai Zhou, Guoyang Xu, Alexander Miglo, Daizong Li, Tong Chen, Baiming Guo and Chuni Ghosh Princeton Optronics, 1 Electronics Drive, Mercerville, NJ, USA 08619 ABSTRACT There has been increased interest in vertical-cavity surface-emitting lasers (VCSELs) for illumination and sensing in the consumer market, especially for 3D sensing ("gesture recognition") and 3D image capture. For these applications, the typical wavelength range of interest is 830~950nm and power levels vary from a few milli-Watts to several Watts. The devices are operated in short pulse mode (a few nano-seconds) with fast rise and fall times for time-of-flight applications (ToF), or in CW/quasi-CW for structured light applications. In VCSELs, the narrow spectrum and its low temperature dependence allows the use of narrower filters and therefore better signal-to-noise performance, especially for outdoor applications. In portable devices (mobile devices, wearable devices, laptops etc.) the size of the illumination module (VCSEL and optics) is a primary consideration. VCSELs offer a unique benefit compared to other laser sources in that they are "surface-mountable" and can be easily integrated along with other electronics components on a printed circuit board (PCB). A critical concern is the power-conversion efficiency (PCE) of the illumination source operating at high temperatures (>50 deg C). We report on various VCSEL based devices and diffuser-integrated modules with high efficiency at high temperatures. Over 40% PCE was achieved in broad temperature range of 0-70 ºC for either low power single devices or high power VCSEL arrays, with sub- nano-second rise and fall time. These high power VCSEL arrays show excellent reliability, with extracted mean- time-to-failure (MTTF) of over 500 years at 60 ºC ambient temperature and 8W peak output. Keywords: VCSEL, high-efficiency, high-power, illumination, time-of-flight, structured light, 3D sensing, 3D image capture, gesture recognition, reliability, diffuser 1. INTRODUCTION Vertical-cavity surface-emitting lasers (VCSELs) have been extensively used for infra-red (IR) illumination applications 1, 2 . Recently, in the fast evolving consumer electronics market, 3D sensing (gesture recognition) and 3D image capture are under intense development and becoming closer to reality 3, 4 . As the preferred IR illumination source, VCSELs have been attracting lots of interest due to its combined advantages in performance, reliability and cost 1, 2 . Specific applications using VCSELs for 3D sensing and imaging include various 3D movement detections such as gesture recognition, face recognition, eye movement recognition as well as 3D photography, laser auto focusing, etc. For those applications, VCSEL can be operated under short pulse mode, long pulse quasi-continuous- wave mode (QCW) mode or even continuous-wave (CW) mode. While the short pulse mode is mainly used for time- of-flight (TOF) 5, 6 based applications, the QCW or CW mode is mostly used for structured light 7 based applications. For either sensing architecture, the peak operating power for VCSELs range from a few mili-Watts to several Watts. Typical lasing wavelengths for those 3D illumination applications are between 830nm and 950nm, in order to work together with the existing mature Si detector technology. We have developed various VCSELs and VCSEL-based modules within such wavelength range, all of which have performance that meet the stringent consumer product’s requirements such as operating under harsh environments. It’s quite advantageous to use VCSEL for such 3D sensing applications. First, the emission spectrum of VCSEL is very narrow, usually less than 1nm at full width half maximum (FWHM). In addition, its temperature dependence is very small, shifting at a rate of 0.065nm/C vs edge emitter’s 0.3nm/C. This allows the use of narrow band filters to remove unwanted background and improve signal-to-noise ratio, which is very attractive for many outdoor applications. 2 nd , VCSEL-based modules can be made with very compact form-factor. In portable devices (mobile devices, wearable devices, laptops etc.) the size of the illumination module (VCSEL and optics) is a primary consideration. For VCSELs, because it’s not necessary to form long resonant cavity and cleaved facet in the lateral directions, therefore the practical limitation on chip dimension can be very small, such as 200um x 200um or even smaller. 3 rd advantage is its easy integration and packaging. VCSELs offer a unique benefit compared to other laser Vertical-Cavity Surface-Emitting Lasers XX, edited by Kent D. Choquette, James K. Guenter, Proc. of SPIE Vol. 9766, 97660D · © 2016 SPIE CCC code: 0277-786X/16/$18 · doi: 10.1117/12.2213295 Proc. of SPIE Vol. 9766 97660D-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 03/14/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx