Collective Micro-Optics Technologies for VCSEL Photonic Integration

Abstract

We describe the main recent technological approaches that associate micro-optical elements to VCSELs in order to control their output beam and to improve their photonic integration. These approaches imply either a hybrid assembly or a direct integration technique. They are compared with regards to their tolerance to alignment errors and to their ease of implementation onto arrays of devices at a wafer level. In particular, we detail the integration techniques we have developed for self-aligned polymer microlens fabrication for beam collimation and short distance beam focusing. Finally, designs to achieve active micro-optics or to exploit novel nanophotonic effects are discussed.

New high-density deformable mirrors for high-contrast imaging

“…Microlens arrays in fused silica with a very good wavefront error (<λ/20 rms in the visible) and very accurate centering (<0.5 μm) are commercially available, but a dedicated microoptical lens manufacturing can be achieved for each VCSELs laser (see Bardinal et al 2011) to allow the best possible lens centering, with high-precision microelectronic technology.…”

“…3. Because the device uses a VCSELs array (Kasten et al 2007;Seurin et al 2008;Bardinal et al 2011) to exercise pressure on the thick membrane via laser beams, it is essential to take into account any possible diffraction effects; these calculations are given in Sect. 4.…”

Study of SU-8 reliability in wet thermal ambient for application to polymer micro-optics on VCSELs

“…[1][2][3][4] It is indeed mandatory to associate these laser devices to micro-optical elements to meet most of systems requirements on beam divergence reduction or on beam focusing. 5) Early reports on microoptics association to VCSELs were mainly based on hybrid assembly methods. Nonetheless, these methods require tricky alignment steps and are often not compatible with high density VCSELs arrays.…”

Microlens self-writing on vertical laser diodes by Near Infra-Red photo-polymerization

“…VCSELs are associated to external micro-optical elements to adapt their natural far-field beam divergence (from 10° to 22° half angle at 1/e², depending on fabrication technology) to the aimed application. Consequently, VCSEL beam shaping using collective and simple methods is strongly in demand [3]. In particular, beam focusing up to the diffraction limit stays a key issue for exploiting singlemode VCSELs for sensing, measurement or printing [4][5].…”