Oxide-aperture-dependent output characteristics of circularly symmetric VCSEL structure

Abstract

The influence of oxidation aperture on the output characteristics of the circularly symmetric vertical-cavity-surface-emitting laser (VCSEL) structure is investigated. To do so, VCSELs with different oxide aperture sizes are simulated by the finite-difference time-domain (FDTD) method. The relationships among the field distribution of mode superposition, mode wavelength, output spectra, and far-field divergence with different oxide apertures are obtained. Further, VCSELs respectively with oxide aperture sizes of 2.7 μm, 4.4 μm, 5.9 μm, 7 μm, 8 μm, 9 μm, and 18.7 μm are fabricated and characterized. The maximum output power increases from 2.4 mW to 5.7 mW with oxide aperture increasing from 5.9 μm to 9 μm. Meanwhile, the wavelength tuning rate decreases from 0.93 nm/mA to 0.375 nm/mA when the oxide aperture increases from 2.7 μm to 9 μm. The thermal resistance decreases from 2.815 °C/mW to 1.015 °C/mW when the oxide aperture increases from 4.4 μm to 18.7 μm. It is demonstrated theoretically and experimentally that the wavelength spacing between adjacent modes increases with the augment of the injection current and the spacing becomes smaller with the oxide aperture increasing. Thus it can be reported that the aperture size can effectively reduce the mode overlaying but at the cost of the power decreasing and the wavelength tuning rate and thermal resistance increasing.

Determination of electrical and thermal parameters of vertical-cavity surface-emitting lasers

“…The analysed VCSEL has an electrical aperture of about 5 μm. According to the literature data, VCSELs produced from arsenide material with similar apertures have thermal resistances in the range 0.5-2.8 K/mW [18][19][20]. Therefore, we can conclude that the analysed laser has good, relatively low thermal resistance.…”

Targeted defect analysis in VCSEL oxide windows using 3D slice and view

“…For scalable production of VCSELs in industry, arrays of hundreds or thousands of devices are fabricated across a wafer and it is well known that it is hard to maintain uniformity of the oxide aperture dimensions in different devices [8]. Consequently any slight difference in the aperture shape/size or structural defect will inevitably result in varied performance between devices, such as laser output power and mode overlapping [9,10]. In addition, design or fabrication process induced defects in the multilayer structure, top surface and connections are important for assessment of the device quality.…”