Open AccessMonolithic Microlens VCSELs With High Beam Quality
Author(s) -
Youwen Huang,
Xing Zhang,
Jianwei Zhang,
Yiyang Xie,
Werner Hofmann,
Yongqiang Ning,
Lijun Wang
Publication year - 2017
Publication title -
ieee photonics journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 73
eISSN - 1943-0655
pISSN - 1943-0647
DOI - 10.1109/jphot.2017.2719702
Subject(s) - engineered materials, dielectrics and plasmas , photonics and electrooptics
In this paper, we report on high beam quality vertical-cavity surface-emitting lasers (VCSELs) featuring a monolithically integrated aspherical microlens. This lens is fabricated by a one-step diffusion-limited wet etch process. VCSELs with microlenses with different curvature radius are designed, fabricated, and characterized, as well as reference VCSEL devices without the microlens. Significant improvement of beam divergence and single-mode performance are demonstrated in microlens VCSELs. The divergence angles of a conventional VCSEL are 14.5°, 16.0°, and 17.0° (full width at D4σ) at 2 mA, 3 mA, and 4 mA, respectively, with a M2 value measured to be 6.9 at 3 mA. Under the same current injection, the divergence angles of a comparable VCSEL with a micro-lens (curvature radius of 31.8 μm) are reduced to 4.8°, 5.5°, and 5.7°, respectively. The M2 value of the lensed VCSEL is as low as 1.9 at 3 mA.