Selectively oxidized InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSEL) array at an emission wavelength of 980nm was reported. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.21W at room temperature, resulting in 1KW/cm<sup>2</sup> average optical power density. The device threshold current is 1.32A The lasing peak wavelength is 981.9 nm, the full width at half-maximum is 0.7 nm, and the far-field divergence angle is about 17<sup>o</sup>.The characteristics of a single device with a active region diameter of 800μm is compared with that of a 2-D array with active region diameter of individual element of 200μm. These two kinds of devices have the same total lasing area. At the same current injection, the single device has a higher threshold and a higher output power than the array. The red shift of single device is more obvious than that of the array's.
Long wavelength InGaAs/InGaAsP MQW wafers are grown by MOCVD technique. Novel structure microcavity laser is fabricated with this MQW material. This microcavity laser is integrated with one or two directional output waveguides, which is connected to the microcylinder or microring. The diameter of microcylinder laser is 10 to 60 micron and the width of the directional waveguide is 10μm with a length of 300micron. Low threshold current of 5mA and multi-mode lasing emission is realized in pulsed operation.
The high power bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) with a wavelength of 980nm are described. The device has been fabricated by using oxidation confinement technology. Al2O3 film, instead of SiO2 film is used as the passivation layer to enhance heat dissipation. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance is discussed.
Long wavelength InGaAs/InGaAsP multiple quantum well laser is grown by MOCVD. The characteristics of spontaneous emission, amplified spontaneous emission and modal gain of the MQW is investigated by using single-pass multi-section technique. The amplified spontaneous emission is around a wavelength of 1500nm, dependent on the temperature and the current density. The modal gain spectra show a red shift with increasing temperature. The peak modal gain exhibits a decrease with increasing temperature from 140K to 300K. The loss measurements shows that the main loss mechanism in the structure might be the free carrier absorption in the doped cladding layers and a internal modal loss of about 10cm<sup>-1</sup>.