Lateral feeding design and selective oxidation process in vertical cavity transistor lasers (oxide-VCTLs) are developed for improving spatial current and optical modes confinement to achieve low threshold operation. Oxide-VCTLs with oxide apertures of 6.4 × 7.4 μm2 and 4.5 × 5.6 μm2 deliver threshold of 1.3 and 1.6 mA, respectively. The smaller oxide-VCTL exhibits a larger mode spacing of 1.02 nm and achieves a better side-mode suppression ratio of 37 dB. The low threshold oxide-VCTL with a high quality factor (Q) cavity shows a gradual current gain (β) compression when the transistor base recombination shifts from spontaneous to coherent stimulated emission as compared with a sharp β compression previously reported in a high threshold edge-emitting transistor laser with a lower "Q" cavity.
ASJC Scopus subject areas
- Physics and Astronomy(all)