Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
  • CLEO/Europe and EQEC 2011 Conference Digest
  • OSA Technical Digest (CD) (Optica Publishing Group, 2011),
  • paper CB8_5

Singlemode tunable VCSELs with integrated MEMS technology

Not Accessible

Your library or personal account may give you access

Abstract

A simple MEMS technology for wafer-scale integration of tunable VCSELs is presented in Fig. 1 a) [1]. The tunable VCSEL is composed of a ”half-VCSEL”, which is a VCSEL without top distributed Bragg reflector (DBR), and an external mirror, which is a micromachined membrane (”MEMS”). The GaAs-based half-VCSEL comprises a bottom DBR, an active region with 5 quantum wells (QWs), and an oxide aperture for current confinement. The etched mesa is capped with an antireflection coating (AR-c) and embedded in a low-k dielectric (BCB). Reflown photo-resist droplets are used as sacrificial layer and as preform for making curved micro-mirrors, as shown in Fig. 1 b). A dielectric DBR (7.5 pairs TiO2/SiO2) and an actuation layer (50 nm Ni) are deposited onto the half-VCSEL, and then the MEMS structure is etched. Finally, the mirror membrane is released by dissolving the sacrificial layer in acetone and removing the liquid in a critical point dryer. The VCSEL is tuned by injecting a heating current into the actuation layer on the flexible MEMS, which expands and shifts the cavity resonance towards longer wavelengths. In the following we present an optimized half-symmetric cavity design for singlemode emission. Compared to [1] the mesa diameter is enlarged (from 120μm to 200μm) to increase (i. e. flatten) the radius of curvature (RoC) from 420μm to 1.2 mm, while keeping the air-gap at around 3.7 μm. The threshold gain of fundamental mode and higher order mode during tuning are simulated (Fig. 1 c)) using a 3D model based on coupled mode theory [2]. The resulting gain difference for different oxide aperture diameters Doxis plotted in Fig. 1 d). The cavity supports the single fundamental mode for Dox10 μm, while the more expanded higher order transverse modes suffer from clipping at the oxide aperture (for Dox5 μm the fundamental mode is affected, too). A microscope image of a fully processed tunable VCSEL is shown in Fig. 1 e). Each chip contains an array of 8 ×8 tunable VCSELs with a small footprint of 290 μm × 400 μm. The spectrum of a tunable VCSEL with 10μm oxide aperture is shown in Fig. 1 f). The VCSEL emits in fundamental mode with a sidemode suppression ratio SMSR 25 dB over the tuning range of 12 nm. In comparison, conventional non-tunable 850-nm VCSELs with flat top DBR are singlemode only for Dox3 μm and usually operated at higher current densities.

© 2011 Optical Society of America

PDF Article
More Like This
Singlemode 50nm Tunable Surface Micro-Machined MEMS-VCSEL Operating at 1.95 μm

K. Zogal, T. Gruendl, C. Gierl, C. Grasse, H. A. Davani, G. Boehm, P. Meissner, F. Kueppers, and M.-C. Amann
CTu3N.1 CLEO: Science and Innovations (CLEO_SI) 2012

Tuning dynamics of a > 70 nm continuously tunable MEMS-VCSEL with a hybrid curved mirror

K. Zogal, C. Gierl, H. A. Davani, C. Grasse, M. Maute, P. Meissner, and M.-C. Amann
CB11_6 The European Conference on Lasers and Electro-Optics (CLEO_Europe) 2011

Widely Electro Thermal Tunable Bulk-Micromachined MEMS-VCSEL Operating around 850nm

Hooman A. Davani, Christian Grasse, Benjamin Kögel, Christian Gierl, Karolina Zogal, Tobias Gründl, Petter Westbergh, Sandro Jatta, Gerhard Böhm, Peter Meissner, Anders Larsson, and Markus-Christian Amann
C829 Conference on Lasers and Electro-Optics/Pacific Rim (CLEOPR) 2011

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Select as filters


Select Topics Cancel
© Copyright 2022 | Optica Publishing Group. All Rights Reserved