MEMS VCSEL Technology

MEMS VCSEL

What Is a MEMS VCSEL and How Does It Work?

The OCTLIGHT VCSEL Swept Source is based on a semiconductor laser diode with an integrated wavelength sweeping mechanism. The laser diode is a Vertical-Cavity Surface-Emitting Laser (VCSEL) that has single-mode light emission and a long coherence length. The wavelength sweep is implemented using a Micro-Electro-Mechanical System (MEMS) to change the length of the laser cavity by which a stable and rapid wavelength sweep results.

Due to their high reliability and unique Gaussian beam profile, 8xx-9xx nm VCSELs have become a cornerstone in datacom using active optical cables (AOC) for cloud computing and now also in 3D imaging using time-of-flight (ToF) and VCSEL arrays for smartphones and automotive. LiDAR is the latest application area where VCSELs are being deployed for both ToF and Frequency-Modulated Continuous Wave (FMCW).

What Is the Reliability of a MEMS VCSEL?

Before the introduction of Texas Instruments Digital Micromirror Devices (DMD) MEMS was seen as a technology with potential reliability issues due to the micro-mechanical moving element, but since then the often-superior reliability has been proven in numerous applications from the DMD to MEMS timing solutions where billions of units have been shipped with failure rates less than 1 defective parts per million (DPPM). MEMS has been widely commercialized within both automotive and consumer applications especially driven by pressure sensors and inertial measurement units (IMUs).

Reliability of VCSEL and MEMS has been extensively investigated and operating lifetime of 10,000 to 100,000 hours have been demonstrated for commercial products. The VCSEL technology further has the advantages of wafer-scale testing which reduces packaging cost while ensuring high quality.

What Research Is OCTLIGHT´s Patented Wavelength Tunable Laser Technology Based on?

The OCTLIGHT technology is based on research performed at The Technical University of Denmark (DTU). The Department of Photonics at DTU was the first in the world to demonstrate a tunable and electrical pumped VCSEL at 1060 nm. OCTLIGHT has exclusive license to the patent applications protecting the key unique features.

T. Ansbaek, I. Chung, E. S. Semenova and K. Yvind, “1060-nm Tunable Monolithic High Index Contrast Subwavelength Grating VCSEL,” in IEEE Photonics Technology Letters, vol. 25, no. 4, pp. 365-367, Feb.15, 2013, doi: 10.1109/LPT.2012.2236087.

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T. Ansbæk, I. Chung, E. S. Semenova, O. Hansen and K. Yvind, “Resonant MEMS Tunable VCSEL,” in IEEE Journal of Selected Topics in Quantum Electronics, vol. 19, no. 4, pp. 1702306-1702306, July-Aug. 2013, Art no. 1702306, doi: 10.1109/JSTQE.2013.2257164.

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What Is Unique about OCTLIGHT´s VCSEL Swept Source?

The OCTLIGHT VCSEL Swept Source is unique in using monolithic MEMS-VCSELs similar to 9xx nm datacom VCSELs and a single material MEMS system similar to proven MEMS timing solutions. The Caliper VCSEL Swept Source is a complete subsystem which includes efficient optical coupling and amplification of the VCSEL together with wavelength sweeping of the MEMS using low voltages.

For applications where a flexible scan rates is desired, such as to switch between several scan modes, we offer the Swept Source Caliper-FLEX.

For applications where a fixed scan rate is needed, we offer the Swept Source Caliper-HERO. The patented Highly Efficient Resonant Oscillator (HERO™) technology achieves fast scan rates into the MHz range by operating the MEMS in vacuum with a simple and low-voltage drive signal. This provides several benefits including:

High phase stability
Long-term stable wavelength sweep
Symmetric bi-directional sweep
High reliability due to the absence of MEMS catastrophic failure

The long-term stability makes efficient high throughput data acquisition possible using a single-channel DAQ with pre-calibrated FFT linearization.

What Form Factors of VCSEL Technology Are Required?

Depending on the final application different form factors may be required. The VCSEL is uniquely positioned to be integrated from highly miniaturized Photonic Integrated Circuits (PIC) to sophisticated optical fiber or free-space instruments.

Optical systems can be made with free-space optics or fiber optics for devices for small to medium volume applications where size constraints are relaxed. The VCSEL can easily be packed in a TO package for free space and pigtailed for fiber delivery which forms the basis of the optical integration in the VCSEL Swept Source. Light sources with fiber output are easy to work with and integrate in any optical system. The VCSEL Swept Source from OCTLIGHT comes with a single-mode fiber and interface to contact to any optical imaging system.

Recently there has been a rapid development in Photonics Integrated Circuits which offers the possibility to integrate optical functionality known from optical fiber and free-space system into a single chip. This is advantageous for large volume applications where size is a constraint. The small VCSEL chip area of 250×250 um and surface-emission makes it possible to integrate using direct transfer technology to PICs with efficient optical coupling to surface gratings.

MEMS VCSEL

What Is a MEMS VCSEL and How Does It Work?

What Is the Reliability of a MEMS VCSEL?

What Research Is OCTLIGHT´s Patented Wavelength Tunable Laser Technology Based on?

What Is Unique about OCTLIGHT´s VCSEL Swept Source?

What Form Factors of VCSEL Technology Are Required?

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