Optical homodyne RZ-QPSK transmission through wind tunnel at 3.8 and 1.55 micron via wavelength conversion

Pak S. Cho; Geof Harston; Kai-Daniel F. Büchter; David Soreide; Jonathan M. Saint Clair; Wolfgang Sohler; Yaakov Achiam; Isaac Shpantzer

doi:10.1117/12.810498

9 May 2009 Optical homodyne RZ-QPSK transmission through wind tunnel at 3.8 and 1.55 μm via wavelength conversion

Pak S. Cho, Geof Harston, Kai-Daniel F. Büchter, David Soreide, Jonathan M. Saint Clair, Wolfgang Sohler, Yaakov Achiam, Isaac Shpantzer

Author Affiliations +

Proceedings Volume 7324, Atmospheric Propagation VI; 73240A (2009) https://doi.org/10.1117/12.810498
Event: SPIE Defense, Security, and Sensing, 2009, Orlando, Florida, United States

Abstract

Atmospheric absorption, scattering, and turbulence are impairments in practical high-speed free-space laser communications. These atmospheric effects can be mitigated by choosing the proper transmission wavelength. It is well known that the MWIR (~3.8 μm) has many low-absorption spectral lines suitable for low-loss propagation. Also, MWIR can be more robust to turbulence in the weak-turbulence regime. Since high-speed laser transceivers are not available in the MWIR, a 3.8-μm signal can be generated and detected using a 1.55-μm telecom transceiver via wavelength conversion. Free-space transmission of optical homodyne RZ-QPSK through a turbulent channel at 3.8 μm has been investigated. A pair of Ti:PPLN-based nonlinear wavelength converters were used to down- and up-convert from 1.55 to 3.8 and back to 1.55 μm at the transmitter and at the homodyne receiver, respectively. The converted RZQPSK signal was transmitted through a tabletop wind tunnel that produces a weak turbulent path. Comparison of 1.55 and 3.8 μm transmission through the wind tunnel shows that under weak-turbulence 3.8 μm transmission is more robust than 1.55 μm. Under the same turbulence condition, the scintillation index measured at 3.8 μm is consistently lower than that at 1.55 μm. Extrapolated scintillation indexes for 3.8 and 1.55 μm using the Rytov variance (~ λ^-7/6 ) and independent measurement at 632.8 nm are consistent with the RZ-QPSK scintillation data for 3.8 and 1.55 μm. Under the most severe turbulence condition, the average bit-error-rate of 3.8-μm transmission is better than that of 1.55-μm giving an estimated receiver sensitivity improvement of at least 6 dB.

Citation Download Citation

Pak S. Cho, Geof Harston, Kai-Daniel F. Büchter, David Soreide, Jonathan M. Saint Clair, Wolfgang Sohler, Yaakov Achiam, and Isaac Shpantzer "Optical homodyne RZ-QPSK transmission through wind tunnel at 3.8 and 1.55 μm via wavelength conversion", Proc. SPIE 7324, Atmospheric Propagation VI, 73240A (9 May 2009); https://doi.org/10.1117/12.810498

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