NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Multilayer Dielectric Transmissive Optical Phase ModulatorA multilayer dielectric device has been fabricated as a prototype of a low-loss, low-distortion, transmissive optical phase modulator that would provide as much as a full cycle of phase change for all frequency components of a transmitted optical pulse over a frequency band as wide as 6.3 THz. Arrays of devices like this one could be an alternative to the arrays of mechanically actuated phase-control optics (adaptive optics) that have heretofore been used to correct for wave-front distortions in highly precise optical systems. Potential applications for these high-speed wave-front-control arrays of devices include agile beam steering, optical communications, optical metrology, optical tracking and targeting, directional optical ranging, and interferometric astronomy. The device concept is based on the same principle as that of band-pass interference filters made of multiple dielectric layers with fractional-wavelength thicknesses, except that here there is an additional focus on obtaining the desired spectral phase profile in addition to the device s spectral transmission profile. The device includes a GaAs substrate, on which there is deposited a stack of GaAs layers alternating with AlAs layers, amounting to a total of 91 layers. The design thicknesses of the layers range from 10 nm to greater than 1 micrometer. The number of layers and the thickness of each layer were chosen in a computational optimization process in which the wavelength dependences of the indices of refraction of GaAs and AlAs were taken into account as the design was iterated to maximize the transmission and minimize the group-velocity dispersion for a wavelength band wide enough to include all significant spectral components of the pulsed optical signal to be phase modulated.
Document ID
20110020338
Acquisition Source
Marshall Space Flight Center
Document Type
Other - NASA Tech Brief
External Source(s)
http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=/Briefs/Nov04/MSC31565.html
Authors
Keys, Andrew Scott (NASA Marshall Space Flight Center Huntsville, AL, United States)
Fork, Richard Lynn (Alabama Univ. Huntsville, AL, United States)
Date Acquired
August 25, 2013
Publication Date
November 1, 2004
Publication Information
Publication: NASA Tech Briefs, November 2004
Subject Category
Man/System Technology And Life Support
Report/Patent Number
MFS-31565
Distribution Limits
Public
Copyright
Public Use Permitted.

Related Records

IDRelationTitle20110020330Collected WorksNASA Tech Briefs, November 2004
No Preview Available