OCT System with Bonded MEMS Tunable Mirror VCSEL Swept Source

Abstract

A microelectromechanical systems (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) in which the MEMS mirror is a bonded to the active region. This allows for a separate electrostatic cavity, that is outside the laser's optical resonant cavity. Moreover, the use of this cavity configuration allows the MEMS mirror to be tuned by pulling the mirror away from the active region. This reduces the risk of snap down. Moreover, since the MEMS mirror is now bonded to the active region, much wider latitude is available in the technologies that are used to fabricate the MEMS mirror. This is preferably deployed as a swept source in an optical coherence tomography (OCT) system.

Description

BACKGROUND OF THE INVENTION[0001]Optical coherence analysis relies on the use of the interference phenomena between a reference wave and an experimental wave or between two parts of an experimental wave to measure distances and thicknesses, and calculate indices of refraction of a sample. Optical Coherence Tomography (OCT) is one example technology that is used to perform high-resolution cross sectional imaging. It is often applied to imaging biological tissue structures, for example, on microscopic scales in real time. Optical waves are reflected from an object or sample and a computer produces images of cross sections or three-dimensional volume renderings of the sample by using information on how the waves are changed upon reflection.[0002]There are a number of different classes of OCT, but Fourier domain OCT currently offers the best performance for many applications. Moreover, of the Fourier domain approaches, swept-source OCT has distinct advantages over techniques such as spe...

AI Technical Summary

Benefits of technology

The present invention is about a MEMS tunable VCSEL that has a bonded MEMS mirror and an electrostatic cavity outside the laser's optical resonant cavity. This allows for tuning of the MEMS mirror without the risk of snap down and allows for wider technology options for the MEMS mirror. The technical effect of this invention is better control over the tuning of the tourable VCSEL.

Problems solved by technology

Monolithically forming the MEMS electrostatically actuated dielectric mirror over the active region creates a number of disadvantages, however.

Another problem is that since the optical cavity and the electrostatic cavity overlap at least to some degree, the MEMS mirror is tuned by pulling the mirror toward the active region.

If too much voltage is applied, this mirror will then snap down and possibly adhere to the active region destroying or damaging the MEMS tunable VCSEL.

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