Vixar (United States)

Multijunction VCSELs with up to eight active regions are fabricated with integrated surface relief features for transverse mode suppression. Using this approach, we demonstrate a single mode 940nm VCSEL with a record high power of 14.2 and SMSR >30dB during room temperature, continuous wave operation.

We demonstrate a miniature VCSEL-based light source with optical power output that varies by less than 50 ppm/°C over a 40°C temperature range. This represents a ten-fold improvement in control accuracy over what is achieved by the best available light sources with semiconductor emitters. A single-mode, polarization-locked, 670-nm VCSEL (Vixar, Inc.) is used to demonstrate the feasibility of the light source. The critical component of our control system is a beamsplitter formed by a wedge of fused silica with a weakly-polarizing, interference coating. A wedge shape eliminates fluctuations in optical power caused by interference fringes and the normal incidence of the exit beam removes polarization dependency as well as the need for an anti-reflective coating. The beamsplitter is in a closed control loop that enables compensation for control errors caused by changes in photodetector responsivity, emission wavelength, and beam divergence with temperature. We also show that careful attention to optical and mechanical alignment is essential to realize the performance enhancements reported herein. Angular tolerances of ±0.05°are required and most coating houses lack the metrology capabilities to characterize the TCB coating with such high tolerances. A discrete-wavelength reflectometer was developed for this purpose.

Red VCSELs are of interest for medical and industrial sensing, printing, scanning, and consumer electronics applications. This paper will describe the optimization of red VCSEL design to achieve improved output power and a broader temperature range of operation. We will also discuss alternative packaging approaches and in particular will describe non-hermetic packages and performance of the VCSELs in a humid environment. Record output power of 14mW CW and a record maximum temperature of operation of 105°C have been achieved at an emission wavelength of 680nm. The achievement is the result of attention to many details including resonance cavitygain peak offset, material choices, current and mode confinement approaches, and metal aperture design. We have also demonstrated lifetimes >1000 hours for non-hermetic packages in an 85% humidity environment. A chip on board approach has been used to create a large scale linear array of VCSELs for a scanning application.