Tech Briefs

Optical Tunable-Based Transmitter for Multiple High-Frequency Bands

Applications include satellite communications, optical communications networks, and RF antenna applications.

The purpose of this innovation is to be able to deliver, individually or simultaneously, multiple microwave high-frequency bands including, but not limited to, L (1.5 GHz), C (7 GHz), X (8.4 GHz), Ku (14.5 GHz), Ka (32 GHz), and Q (38 GHz) frequencies at high data rates and with minimal hardware, particularly for use in satellite-to-satellite communications applications. Additionally, this innovation would be a satellite-based transmitter with a significant reduction in weight, mass, and power when compared to current, conventional technologies.

The apparatus is comprised of a multiple- wavelength, tunable laser that has the capability to tune the lasing wavelengths independently or simultaneously; a de-multiplexing/optical filter to retrieve individual wavelengths at the receiving end; an electro-optic modulator to modulate individual wavelengths with the desired microwave frequencies; and a multiplexer that combines the modulated optical frequency bands into a single output optical fiber.

Although the multi-wavelength, tunable laser can generate a set of up to 40 wavelength channels, in this experimental demonstration, only six wavelength channels are illustrated: λ1=1,550 nm, λ2=1,550.2 nm, λ3=1,550.4 nm, λ4=1,550.6 nm, λ5=1,550.8 nm, and λ6=1,552 nm. These six wavelength channels can then be mapped to the corresponding frequency bands L, C, X, Ku, Ka, and Q, to produce the mapping table configuration described by the following: λ1= L band, λ2 =C band, λ3 = X band, λ4 = Ku band, λ5 = Ka band, and λ6 = Q band.

For instance, when three frequency bands, such as C, Ku, and Ka, are assigned or allocated for signal transmission on a satellite terminal, the wavelength controller function, using the mapping table configuration, is to switch on the wavelength channels that only correspond to those allocated frequencies, which results in generating three wavelength channels: λ2, λ4, and λ5.

This work was done by Hung D. Nguyen, Rainee N. Simons, Edwin G. Wintucky, and Jon C. Freeman of Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. LEW-19072-1