Oscillation element, oscillator, and imaging apparatus using the same

Abstract

An oscillation element includes an antenna for oscillation configured to oscillate electromagnetic waves, and multiple negative resistance elements electrically connected to the antenna in parallel, and the multiple negative resistance elements are disposed in only a place where the phases of electromagnetic waves oscillated therefrom are the common phase or opposite phase.

What is claimed is: 
     
         1 . An oscillation element configured to oscillate electromagnetic waves, the oscillation element comprising:
 an antenna including a resonator which resonates with the electromagnetic waves and configured to guide the electromagnetic waves; and   a first negative resistance element electrically serially connected to the antenna, and   a second negative resistance element electrically serially connected to the antenna and being electrically parallel to the first negative resistance element,   wherein the first negative resistance element is disposed in a position of a wave front of the electromagnetic waves with which the resonator resonates, in such a manner that an absolute value of a phase difference between a phase of the wave front of the electromagnetic waves with which the resonator resonates in the position where the first negative resistance element is disposed and a phase of a wave front of the electromagnetic waves with which the resonator resonates in a position where the second negative resistance element is disposed becomes 0 or greater and π/8 or less, or the absolute value becomes 7π/8 or greater and 9π/8 or less.   
     
     
         2 . The oscillation element according to  claim 1 , wherein the antenna includes a conductor and a semiconductor layer, and
 wherein each of the first negative resistance element and the second negative resistance element is electrically serially connected to the conductor via the semiconductor layer.   
     
     
         3 . The oscillation element according to  claim 1 , wherein the antenna includes a first conductor and a second conductor, and
 wherein each of the first negative resistance element and the second negative resistance element is in contact with the first conductor.   
     
     
         4 . The oscillation element according to  claim 1 , wherein a plurality of negative resistance elements including the first negative resistance element and the second negative resistance element is disposed in an arc shape. 
     
     
         5 . The oscillation element according to  claim 4 , wherein the arc forms line symmetry with an axis parallel to a resonance direction of the electromagnetic waves as a boundary. 
     
     
         6 . The oscillation element according to  claim 1 , wherein an area of a cross section perpendicular to a direction where current of a junction portion forming the first negative resistance element flows is equal to an area of a cross section perpendicular to a direction where current of a junction portion forming the second negative resistance element flows. 
     
     
         7 . The oscillation element according to  claim 1 , wherein a plurality of negative resistance elements including the first negative resistance element and the second negative resistance element is linearly disposed. 
     
     
         8 . The oscillation element according to  claim 7 , wherein an area of a cross section perpendicular to a direction where current of a junction portion forming the first negative resistance element flows differs from an area of a cross section perpendicular to a direction where current of a junction portion forming the second negative resistance element flows. 
     
     
         9 . The oscillation element according to  claim 1 , further comprising a third negative resistance element,
 wherein the first negative resistance element is disposed in a position of a wave front of the electromagnetic waves with which the resonator resonates, in such a manner that an absolute value of a phase difference between a phase of the wave front of the electromagnetic waves with which the resonator resonates in the position where the first negative resistance element is disposed and the phase of the wave front of the electromagnetic waves with which the resonator resonates in the position where the second negative resistance element is disposed becomes 0 or greater and π/8 or less, and   wherein the third negative resistance element is disposed in a position of a wave front of the electromagnetic waves with which the resonator resonates, in such a manner that an absolute value of a phase difference between a phase of the wave front of the electromagnetic waves with which the resonator resonates in the position where the third negative resistance element is disposed and the phase of the wave front of the electromagnetic waves with which the resonator resonates in the position where the second negative resistance element is disposed becomes 7π/8 or greater and 9π/8 or less.   
     
     
         10 . The oscillation element according to  claim 1 , wherein each of the first negative resistance element and the second negative resistance element includes silicon. 
     
     
         11 . The oscillation element according to  claim 10 , wherein each of an area of a cross section perpendicular to a direction where current of a junction portion forming the first negative resistance element flows and an area of a cross section perpendicular to a direction where current of a junction portion forming the second negative resistance element flows is 1 μm2 or less. 
     
     
         12 . The oscillation element according to  claim 1 , wherein each of the first negative resistance element and the second negative resistance element includes a compound semiconductor material. 
     
     
         13 . The oscillation element according to  claim 12 , wherein each of the first negative resistance element and the second negative resistance element includes a Group III-V semiconductor material. 
     
     
         14 . The oscillation element according to  claim 13 , wherein each of an area of a cross section perpendicular to a direction where current of a junction portion forming the first negative resistance element flows and an area of a cross section perpendicular to a direction where current of a junction portion forming the second negative resistance element flows is 10 μm2 or less. 
     
     
         15 . The oscillation element according to  claim 1 , wherein each of the first negative resistance element and the second negative resistance element is a resonant tunneling diode. 
     
     
         16 . The oscillation element according to  claim 1 , further comprising a waveguide which is electrically connected to the antenna to transmit electromagnetic waves,
 wherein each of the first negative resistance element and the second negative resistance element is connected to the waveguide.   
     
     
         17 . The oscillation element according to  claim 1 , wherein the antenna has a protrusion, and is disposed so that the protrusion is positioned between the first negative resistance element and the second negative resistance element. 
     
     
         18 . An oscillator configured to oscillate electromagnetic waves, the oscillator comprising:
 the oscillation element according to  claim 1 ; and   a power source unit configured to apply direct-current (DC) voltage to the oscillation element.   
     
     
         19 . An imaging apparatus configured to image an object to be measured using electromagnetic waves, the imaging apparatus comprising:
 the oscillator according to  claim 18  configured to oscillate electromagnetic waves to an object to be measured;   a detector configured to detect electromagnetic waves transmitted through or reflected at the object to be measured, and   an image constructing unit configured to construct an image regarding the object to be measured from information relating to the electromagnetic waves detected by the detector.