USA As Represented by Secretary of the Navy

Catherine H Bulmer

William K Burns

Alan D Kersey

Arthur S Greenblatt

Anthony Dandridge

Ganesh K Gopalakrishnan

William R Burns

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

The manufacture of an optical waveguide device utilizing a fast, accurate method for tuning of the output phase angle of such devices to a desired operating point. Tuning is accomplished by adjusting the accumulated phase along a waveguide arm of the device by removing optical waveguide material using laser ablation. Due to the change in waveguide geometry in the ablated region, the optical phase velocity is changed and thus the optical path length is affected in that section of waveguide, thereby resulting in a change in output phase angle.

Fabrication and phase tuning of an optical waveguide device

An apparatus and method are disclosed for optimizing the modulation efficcy of a remotely-located, polarization-sensitive, integrated optic modulator which is addressed with a non-polarization preserving fiber link. In a preferred embodiment of the invention, the polarization state of an input light beam is changed as a function of first and second control signals that are applied to the polarization controller. The non-polarization preserving fiber link conveys the light beam with the changed polarization state to the integrated optic modulator. The integrated optic modulator modulates the light beam with the changed polarization state as a function of any information signal to develop an intensity modulated optical signal. If no information signal is present, the optical signal from the modulator is not modulated. An output fiber conveys the optical signal from the integrated optic modulator to a locally-positioned detector for detection. In response to this input optical signal, the detector develops a first electrical signal that has a peak-to-peak amplitude proportional to any information signal and a second electrical signal proportional to the mean of the optical signal. This second electrical signal is utilized by a control means to controllably develop first and second control signals which force the polarization controller to change the polarization state of the input light beam so that the light beam at the input of the integrated optic modulator is maintained in a preselected polarization state in order to maintain the modulation efficiency of the integrated optic modulator at its optimum level.

Apparatus and method for optimizing the modulation efficiency of a

An integrated-optic, polarization-selective phase modulator is disclosed. a preferred embodiment of the invention a channel waveguide provides a path therethrough for polarized light having horizontal and vertical polarization components, and an electrode structure is disposed above the channel waveguide and is responsive to the application of a control voltage to the electrode structure for substantially phase modulating only the vertical component of the polarized light.

Integrated-optic, polarization-selective phase modulator

A process of fabricating an optical directional coupler switch for the TE- and TM-mode polarizations at a given wavelength. Initially, a trial set of waveguide fabrication parameters is used to fabricate a series of channel waveguide directional couplers having the same waveguide spacing and differing interaction lengths. The step is repeated for other waveguide spacings. The power splitting ratio of each directional coupler so fabricated is determined for guided light of one of the polarizations at the given wavelength. For each series of directional couplers having a respective common waveguide spacing, the arctangent of the square root of the power splitting ratio versus the interaction length is graphed and the coupling coefficient for the one polarization is found from the graph slope. The log of the coupling coefficients so determined is graphed versus the corresponding waveguide spacings. The previous three steps are repeated for guided light of the other polarization at the given wavelength. The set of waveguide fabrication parameters is varied and all the steps repeated until the desired set of parameters is arrived at for which the graphs of the log of the coupling coefficients versus the corresponding waveguide spacings for guided light of both polarization at the given wavelength coincide.

Growing community of inventors

Springfield, VA, United States of America

Catherine H Bulmer