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The extrinsic parasitics generally limit the modulation bandwidth of vertical cavity surface emitting lasers (VCSELs) for optical data links and interconnects. In this article, the extrinsic parasitics of 850-nm VCSELs are investigated by three different designs: oxide-only (design A), oxide-implant (design B), and oxide-implant with benzocyclobutene (BCB) (design C). The static and dynamic characteristics of all the designs with~7- $\mu \text{m}$ aperture are measured and compared. The maximum modulation bandwidth of design A is only about 12 GHz mainly limited by the large parasitic capacitances. With a proper proton implantation, a thick nonconducting layer is created inside the device with design B, which dramatically reduces the parasitic capacitances, and thus the bandwidth is increased to about 18 GHz. Based on design B, a 4- $\mu \text{m}$ -thick BCB layer with low dielectric constant is employed underneath the bond pad of design C to further reduce the pad capacitance, leading to the highest bandwidth about 24 GHz and the highest modulation current efficiency factor (MCEF) of 10.8 GHz/mA1/2. The microwave reflection coefficient (${S}_{{11}}$) parameters of the three designs are measured and compared. Results indicate that design C has the lowest parasitic capacitances and the highest modulation bandwidth, which is preferred for high-speed VCSELs to obtain good static and dynamic performance. [ABSTRACT FROM AUTHOR]

Greater than 190 °C continuous wave (CW) lasing is achieved from 905 nm high-efficiency vertical cavity surface-emitting lasers (VCSELs). The maximum power conversion efficiency (PCE) of 46.3% for 4 μm VCSELs was demonstrated under the ambient temperature of 30 °C. The maximum PCE decreases only 10% of its value from 30 °C to 90 °C, showing stable high-temperature characteristics. The thermal resistances and active region temperatures of the device versus ambient temperature are determined experimentally. Besides, size-dependent thermal characteristics are also analyzed by characterizing the spectral and spatial properties of devices with various apertures. It is found that the higher the ambient temperature is, the less the number of high-order modes is, and single fundamental mode operation can be realized in 4 μm VCSELs even at a relatively high temperature of 190 °C. The design and characterization of these high-temperature VCSEL devices might present the basis for future laser radar application. [ABSTRACT FROM AUTHOR]

The output characteristics of vertical cavity surface emitting lasers (VCSELs) arrays are largely influenced by temperature. We systematically studied thermal properties in 20-element oxide-confined VCSEL arrays via both theory and experiment. The output power, conversion efficiency, and threshold current dependent on ambient temperatures were measured. According to the relationship of wavelength shift and dissipated power, the device thermal resistance dependent on ambient temperature was obtained. The actual temperature in active region was successfully extracted. A 3-D heat diffusion model was established to simulate temperature distribution accurately. [ABSTRACT FROM AUTHOR]

In-phase coherently coupled proton-implant-defined vertical cavity surface emitting laser (VCSEL) arrays face difficulties in current spreading, resulting in small array scale, low output power, and broad beamwidth. Although patterned metal grids can improve the current spreading, the undesirable out-of-phase mode tends to be dominant in the array. In this letter, by means of engineering the implantation and array parameters, in-phase mode is obtained in large-scale proton-implant-defined arrays with metal grids. Experimental results show that these arrays are operating in in-phase mode with a nominal interelement spacing of 8 \mu \textm and an implantation depth of 2.22 \mu \textm . By using these parameters, a $5\times 5$ in-phase array with a narrow beamwidth (far-field full width at half maximum) of 1.61° is realized. Besides, a $10\times 10$ in-phase array with a beamwidth of 1.89° and an output power of 10.25 mW for the in-phase mode is achieved. The calculation of far fields is performed to confirm the in-phase operation measured results. Such a simple and low-cost technology provides a promising method for preparing large-scale in-phase coherently coupled VCSEL arrays. [ABSTRACT FROM PUBLISHER]