Continuous beam divergence control via wedge-pair for laser communication applications

Keith M. Hinrichs; Alan E. DeCew; Lawrence E. Narkewich; Timothy H Williams

doi:10.1117/12.2084557

16 March 2015 Continuous beam divergence control via wedge-pair for laser communication applications

Keith M. Hinrichs, Alan E. DeCew, Lawrence E. Narkewich, Timothy H Williams

Proceedings Volume 9354, Free-Space Laser Communication and Atmospheric Propagation XXVII; 93540L (2015) https://doi.org/10.1117/12.2084557
Event: SPIE LASE, 2015, San Francisco, California, United States

Abstract

Lasercom terminals often scan an area of uncertainty during acquisition with a wide-divergence beacon beam. Once the terminal has established cooperative tracking with the remote terminal, a narrow divergence beam is used for communication. A mechanism that enables continuous beam divergence control can provide significant size, weight, and power (SWaP) benefits to the terminal. First, the acquisition and the communication beams can be launched from the same fiber so only a single high-power optical amplifier is required. Second, by providing mid-divergences, it eases the remote terminal’s transition from the acquisition phase to the communication phase. This paper describes a mechanism that provides gradual, progressive adjustment of far-field beam divergence, from wide divergence (> 300 μrad FWHM) through collimated condition (38 μrad FWHM) and that works over a range of wavelengths. The mechanism is comprised of a variable-thickness optical element, formed by a pair of opposing wedges that is placed between the launch fiber and the collimating lens. Variations in divergence with no beam blockage are created by laterally translating one wedge relative to a fixed wedge. Divergence is continuously adjustable within the thickness range, allowing for a coordinated transition of divergence, wavelength, and beam power. Measurements of this low-loss, low-wavefront error assembly show that boresight error during divergence transition is maintained to a fraction of the communication beamwidth over wavelength and optical power ranges.

Citation Download Citation

Keith M. Hinrichs, Alan E. DeCew, Lawrence E. Narkewich, and Timothy H Williams "Continuous beam divergence control via wedge-pair for laser communication applications", Proc. SPIE 9354, Free-Space Laser Communication and Atmospheric Propagation XXVII, 93540L (16 March 2015); https://doi.org/10.1117/12.2084557

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