Visible (639 nm /spl ngt/ /spl lambda/ /spl ngt/ 661 nm) vertical cavity surface emitting laser diodes

We have recently reported optically-pumped lasing in an InGaP/InAlGaP strained quantum well visible vertical cavity surface emitting laser (VCSEL) with both AlAs/AlGaAs distributed Bragg reflectors (DBRs)~ and with InAlPDnAlGaP DBRs2. We have also studied the critical issues for electrical injection in these promising devices and now report the demonstration of the first visible VCSEL diodes. At room temperature with pulsed excitation, the devices lase in a single longitudinal mode within 639.1 nm to 660.7 nm, depending on wafer position. The structures were grown by metalorganic vapor-phase epitaxy (MOVPE) on GaAs substrates and consist of an InAlGaP optical cavity active region surrounded by AlGaAs DBRs. The bottom Si-doped DBR consists of 55.5 periods of alternating AlAs and Al,Gal-,As (x = 0.5) quarter-wave layers with x = 0.75 barrier reduction layers at each interface to reduce series resistance. An identical 36 period C-doped top coupling DBR is used and includes a (p+) GaAs metal contact layer. The InAlGaP optical cavity contains three In0.56Gao.& strained quantum wells in a step graded-barrier separate confinement configuration. Device injection efficiency was optimized by studying the performance of edge-emitting lasers with InAlGaP active regions and AlGaAs DBR cladding layers. Gain-guided "etched post" test devices were fabricated. A top annulus contact defines emitting diameters of 10 pm and 20 pm with a 5 pm radial thickness, thus, a large percentage of the injected current does not directly contribute to lasing but to device heating. Despite this, lasing wavelengths from 639.1 nm to 660.7 nm were measured, on unrotated wafers, at room temperature without heat-sinking. The pulsed excitation was - 100 ns pulses at 10 kHz to IMHz. Many devices continued lasing with up to a 40% duty cycle at 1MHz. The larger devices typically have a threshold of 30 mA at 2.7 V. The peak output power is 3.38 mW with a resistance of less than 15 0. Substantially improved performance is expected with more sophisticated device processing techniques. This is the first demonstration of InAlGaP visible VCSEL diodes. This work opens the door for advanced device applications such as plastic fiber communications, arrays for displays, interconnects, and holographic memory, and some scanning applications in place of HeNe lasers.