USA as Represented by Secretary of the Navy

Other

Ganesh K Gopalakrishnan

William K Burns

Robert P Moeller

Catherine H Bulmer

Robert W McElhanon

William R Burns

A transmission system responsive to an electrical input information signal ncludes means for modulating the input signal with a microwave subcarrier signal to produce a subcarrier modulated signal. A first interferometric modulator responsive to a source light and to the subcarrier modulated signal produces a first modulated optical signal. A second interferometric modulator cascade coupled to the first modulator and being responsive to the first modulated optical signal and to a microwave local oscillator signal produces a second modulated optical signal. Means coupled between the first and second modulators transmit the first modulated optical signal from the first modulator to the second modulator. Means responsive to the second modulated optical signal produce an output signal.

Fiber optic digital transmission system

An optical link is disclosed that is operated by a balanced detection technique so as to extend its linear dynamic range, yet substantially eliminate even-order harmonic distortion of the modulated signal. The modulator comprises two parallel arranged Mach-Zehnder interferometers that respectively have a steady state DC voltage bias applied so that the operating points of the Mach-Zehnder interferometers are selected to produce two separate modulated signals, one of which is later phase shifted by a phase shift device so as to provide an output that is combined with the other modulated signal in such a manner so as to cause a subtraction, leaving the final output signal substantially free of any unwanted even-order harmonic components in order to provide for a multi-octave response characteristic.

Multi-octave, high dynamic range operation of low-biased modulators by

An electro-optic mixer includes means for providing first and second microwave signals having first and second frequencies, respectively, a device for providing a source light, a first modulator responsive to the source light and to the first microwave signal for producing a first modulated optical signal, a second modulator cascade coupled to the first modulator and being responsive to the first modulated signal and to the second microwave signal for producing a second modulated optical signal having a frequency component at the sum or difference or both of the first and second frequencies, and means coupled between the first and second modulators for transmitting the first modulated signal to the second modulator. Each of the first and second modulators is a broadband, low drive voltage, traveling wave intensity modulator including a substrate having a first optical waveguide adapted to receive and transmit light therethrough with a first phase velocity; a buffer layer disposed on the substrate; and a coplanar waveguide electrode structure on the buffer layer for receiving an electrical signal propagating therethrough with a second phase velocity to phase modulate the light in the optical waveguide. The substrate has a sufficiently small thickness so that coplanar mode-substrate mode coupling substantially does not occur, and the coplanar waveguide electrode structure has a sufficiently large thickness so that the first and second phase velocities are equal.

Microwave electro-optic mixer

A broadband, electrooptic modulator is disclosed which, in a first embodiment, comprises: a substrate having substrate modes, having electrooptic effects, and having a first optical waveguide adapted to receive and transmit light therethrough in a first direction and with a first phase velocity; a buffer layer disposed on the substrate; and a coplanar waveguide electrode structure having a coplanar mode and being disposed on the buffer layer for receiving an electrical signal propagating therethrough in the first direction with a second phase velocity to phase modulate the light in the optical waveguide at a frequency in the range from 0 Hz up to substantially 40 GHz. The substrate has a sufficiently small thickness so that coupling between the coplanar mode of the coplanar waveguide electrode structure and any one of the substrate modes of the substrate substantially does not occur over a desired frequency bandwidth of operation, and the coplanar waveguide electrode structure has a sufficiently large thickness so that the second phase velocity of the electrical signal is substantially equal to the first phase velocity. In a second embodiment of the invention an intensity modulator is produced by adding a second optical waveguide which, in combination with the first optical waveguide, forms an interferometer.

Broadband, low drive voltage, electrooptic, intergrated optical modulator

A process for making thick metal structures on a substrate has the steps of: selectively exposing a thick layer of photoresist disposed on a substrate to ultraviolet radiation including the 350 nm to 450 nm portion of tile spectrum of a mercury vapor lamp, where the photoresist layer is a heat-treated arid hydrated photoresist layer, to fully pattern the substrate: developing the patterned substrate by contacting the photoresist layer with a photoresist developing solution; exposing the photoresist layer to a plasma for hardening the pattern against thermal flow; hardbaking the photoresist pattern on the substrate; plating the metal onto the patterned substrate using a low current density (J) during at least part of the plating process, making a thick methyl structure on the substrate.

Growing community of inventors

Lorton, VA, United States of America

Ganesh K Gopalakrishnan