Native-oxide defined ring contact for low threshold vertical-cavity lasers

Abstract

Data are presented characterizing a new process for fabrication of vertical-cavity surface-emitting lasers based on the selective conversion of high Al composition epitaxial AlGaAs to a stable native oxide using ‘‘wet oxidation.’’ The native oxide is used to form a ring contact to the laser active region. The resulting laser active regions have dimensions of 8, 4, and 2 μm. The lowest threshold laser is achieved with the 8-μm active region, with a minimum threshold current of 225-μA continuous wave at room temperature.

Cavity characteristics of selectively oxidized vertical-cavity lasers

“…VCSEL diodes employing an oxide layer under a hybrid top dielectric DBR mirror have also been reported. 4,5 The VCSELs described herein are grown by metalorganic vapor phase epitaxy and employ three InGaAs quantum wells designed to emit near 980 nm with parabolically graded mirror interfaces in the epitaxial DBRs. 8 The high oxidation selectivity of AlGaAs alloys 6 is exploited to form a single buried oxide layer between the active region and the top DBR as depicted in Fig.…”

“…Secondly, the superior electrical and optical confinement will enable fabrication of small area devices producing ultra-low threshold currents. 4,5,11 Finally and perhaps most importantly, the combination of enhanced electrical confinement and the inherent index-guiding in these selectively oxidized VCSELs has led to power conversion efficiencies of greater than 50%, a significant advance in VCSEL performance. 7 In summary, our selectively oxidized all epitaxial VCSEL structure allows the manipulation of the off-axis cavity resonance independent of the as-grown cavity resonance.…”

Modal characteristics of ARROW-type vertical-cavity surface-emitting lasers

“…Most of the previous approaches to achieving single-mode operation have focused on the use of a built-in positive-index waveguide [2]. For such a structure, the cutoff aperture is limited by the device index-step, requiring a relatively small index step to insure single-mode operation.…”

Buried heterostructure vertical-cavity surface-emitting laser with semiconductor mirrors

“…Since their inception, 1 vertical-cavity surface-emitting lasers (VCSELs), have dramatically improved in terms of speed, 2 efficiency, 3 and output power, 4 and are now widely available commercially. One of the principle advantage of VCSELs is a scalable production process, but VCSELs also feature continuous single-mode operation, 5,6 mode-hop free tuning, 7 and improved beam quality 8 compared to edge emitting devices. Nevertheless, reducing VCSEL dimensions into the nanoscale has proved challenging, despite being of great interest for future integration of optics and microelectronics.…”