Measurement of electrical signals with subpicosecond resolution

324-77 SR 7/29/8-5 XR 4? 603* 293

United States Patent m

Mourou et al.

[54] MEASUREMENT OF ELECTRICAL SIGNALS WITH SUBPICOSECOND RESOLUTION

[75] Inventors: Gerard Mourou; Kevin E. Meyer, both of Rochester, N.Y.

[73] Assignee: University of Rochester, Rochester, N.Y.

[21] Appl. No.: 593,992

[22] Filed: Mar. 27,1984

[51] Int. Cl.t G01R 31/00

[52] U.S. CI 324/96; 324/77 K

[58] Field of Search 370/1-4;

350/394, 371, 395, 377, 392, 393, 356; 324/77

K, 77 R, 96, 95

[56] References Cited

U.S. PATENT DOCUMENTS

3,313,938 4/1967 Peters 350/393

3,432,222 3/1969 Fleisher 350/371

3,556,663 1/1971 Cary 350/371

4,166,669 9/1979 Leonberger 350/356

4,360,865 11/1982 Yasumura 324/95

4,446,425 5/1984 Valdmanis 324/77 K

4,510,441 4/1985 Yasuda 350/356

OTHER PUBLICATIONS

Valdmanis, "Picosecond Electro-Optic Sampling System", Appl. Phys. Lett, 41(3), Aug. 1982, pp. 211-212. Valdmanis, "Subpicosecond Electrical Sampling", IEEE Jour, of Quantum Elec, vol. QE19, No. 4, Apr. 1983, pp. 664-667.

[ii] Patent Number: 4,603,293 [45] Date of Patent: Jul. 29, 1986

C. P. Wen, IEEE Trans. Microwave Theory & Tech., 12/69, pp. 1087-1080.

G. Mourou et al., "Subpicosecond Electro-Optic Sampling Using Coplanar Strip Transmission Lines", Appl. Phys. Lett. 45(5), Sep. 1, 1984, pp. 492-494.

Primary Examiner—Michael J. Tokar
Attorney, Agent, or Firm—Martin LuKacher

[57] ABSTRACT

Electrical signals are measured (analyzed and displayed) with subpicosecond resolution by electro-optic sampling of the signal in an electro-optic crystal, the index of which changes in response to the electric field produced by the signal, in accordance with the Pockels effect. The crystal is disposed adjacent to a transmission line along which the signals propagate the line may be a coplanar wave guide having a plurality of parallel strips of conductive material on the surface of the crystal. The crystal may be disposed adjacent to and in the fringe field of a line on a substrate, which may be part of an integrated circuit, for measuring signals propagating along the line during the operation of the circuit. A beam of short optical (laser) sampling pulses in the picosecond range is focused so that the region where the beam is confocal is disposed where the field is parallel in the crystal. The confocal region (where the optical wavefront is planar is preferrably close to the surface of the crystal and perpendicular to the optical axis of the crystal. The optical pulses transmitted through the crystal are processed to provide a display affording a measurement of the electrical signal.

7 Claims, 6 Drawing Figures