Shaping vertical-cavity surface-emitting laser mode profiles with an antiresonant oxide island for improved single-mode emission

Impact of an Antiresonant Oxide Island on the Lasing of Lateral Modes in VCSELs

“…Hence, we conclude that for the analyzed island distances (9th-15th DBR pairs) the overlap between the optical mode and the gain has a negligible impact on the threshold current. The oscillations in the threshold current are similar in character to the oscillations of the cold-cavity modal loss we investigated in [27]. There, we explained such oscillations in terms of the match/mismatch of the optical mode profile with the island aperture.…”

“…In order to understand the real impact of the oxide island on the modal behavior of the analyzed VCSEL, we determine threshold currents for lateral modes of different orders for various island diameters and positions. As stated in the introduction, we performed a similar analysis in a previous study for a cold cavity [27], and demonstrated strong oscillations in the optical losses, mainly in the HE 11 and HE 12 modes. Although the structure was slightly different than that considered in here-the oxide island was located inside the cavity (instead of in the top DBR) and the top DBR was dielectric-the physical mechanism causing these oscillations (the changing of the mode profiles due the differently sized islands) remains the same.…”

“…The resonant cavity is surrounded by 32 pairs of silicon doped n-type DBRs and 24 pairs of carbon doped p-type DBRs made of Al 0.2 Ga 0.8 As/Al 0.9 Ga 0.1 As. In contrast to our previous work [27], we removed the oxidized island from the resonant cavity and placed it inside the subsequent layers of the top DBRs. When analyzing the impact of the island on optical and thermo-electric properties, we changed not only the diameter of the island but also its position.…”

“…In a previous work [27], we introduced an S-ARROW structure directly into the VCSEL cavity, inside the device aperture (i.e., on its axis). The structure was in the form of an oxide island manufactured with a planar oxidation technology [28,29].…”

“…The main drawback of the analysis presented in [27] was the fact that it was a purely cold-cavity analysis, which did not consider the impact of the oxide island on the current flow. In the present article, we address this gap by investigating not only the optical modes but also the current flow and the resulting temperature distribution inside the laser structure.…”