Infrared reflective optical modulator

John A. Coath; Mark A. Richardson

doi:10.1117/12.305497

20 April 1998 Infrared reflective optical modulator

John A. Coath, Mark A. Richardson

Proceedings Volume 3292, Spatial Light Modulators; (1998) https://doi.org/10.1117/12.305497
Event: Optoelectronics and High-Power Lasers and Applications, 1998, San Jose, CA, United States

Abstract

An IR reflective optical modulator has been fabricated. This has been achieved by coating a thick film resistor network with a thin film of vanadium dioxide via a reactive sputtering process. Vanadium dioxide undergoes a semiconductor to metal phase transition at approximately 68 degrees C, therefore to switch the reflective optical modulator the thick film resistors in the network are driven electrically. As the resistors heat up to beyond the transition temperature, the vanadium dioxide undergoes its transition from a transparent semiconductor state to a highly reflective metallic state. Provided the thick film heater network, underneath the vanadium dioxide, is non- reflective, then a significant change in reflectivity is observed upon undergoing the transition, and hence the modulation of reflected IR radiation is achieved. The useful waveband of operation of the device encompasses the region 2-25 micrometers , this is primarily limited by the transparency of the semiconductor state of the vanadium dioxide. Correct stoichiometry of the thin film of vanadium dioxide is critical in producing good modulation depth in the reflective mode. Several devices have been fabricated and tested. They show a reflectivity increase of approximately 13:1 upon switching. The devices to date have demonstrated switch on speeds of 0.1 s and switch off speeds of 0.2 s. This has been achieved without any form of substrate temperature control apart from that produced by the electrical drive. Very slight changes in the stoichiometry of the vanadium dioxide thin film can greatly increase the temperature range and hysteresis of the semiconductor to metal phase transition. This has been utilized to allow partial phase transitions to occur, yielding partial increases in reflectivity, and hence the ability to generate grey levels in the reflected IR radiation.

Citation Download Citation

John A. Coath and Mark A. Richardson "Infrared reflective optical modulator", Proc. SPIE 3292, Spatial Light Modulators, (20 April 1998); https://doi.org/10.1117/12.305497

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available