Optical reflection element with drive and monitor elements separated by a separation groove
An optical reflection element includes a mirror portion and an oscillator coupled to the mirror portion. The oscillator includes a base, an insulating layer, a drive element, and a monitor element. The insulating layer is formed on the base. The drive element and the monitor element are formed on the insulating layer, and are separated from each other by a separation groove. Each of the drive element and the monitor element includes a lower electrode layer, a piezoelectric layer, and an upper electrode layer formed in that order on the insulating layer. The monitor element has high detection accuracy, allowing the optical reflection element to perform self-excited driving with high accuracy.
1. An optical reflection element comprising:
a mirror portion; and
an oscillator coupled to the mirror portion, the oscillator comprising:
a base;
an insulating layer formed on the base;
a drive element and a monitor element formed on the insulating layer, the drive element and the monitor element being separated from each other by a separation groove, wherein
each of the drive element and the monitor element includes a lower electrode layer, a piezoelectric layer, and an upper electrode layer formed in that order on the insulating layer;
the lower electrode layer of the drive element and the lower electrode layer of the monitor element are connected to a same external electrode layer; and
a shortest conductive path between an arbitrary point of the lower electrode layer of the monitor element and an arbitrary point of the lower electrode layer of the drive element adjacent to the monitor element is made larger than a distance from the arbitrary point of the lower electrode layer of the monitor element to the external electrode layer by the separation groove.
2. The optical reflection element of claim 1 , wherein
the separation groove between the drive element and the monitor element has a bottom surface located inside the insulating layer.
3. The optical reflection element of claim 1 , wherein
the separation groove between the drive element and the monitor element has a bottom surface located inside the base.
4. The optical reflection element of claim 3 , wherein
the separation groove is made deeper from an outer periphery thereof toward a center thereof.
5. The optical reflection element of claim 3 , wherein
the separation groove is made deeper from a center thereof toward an outer periphery thereof.
6. The optical reflection element of claim 1 , wherein
a thickness ratio of the insulating layer to the lower electrode layer is made larger than an etching rate ratio of the insulating layer to the lower electrode layer.
7. The optical reflection element of claim 1 , wherein
the oscillator is formed in a meandering shape and includes oscillating plates folded and coupled to each other on a same plane.
8. The optical reflection element of claim 2 , wherein
the separation groove is made deeper from an outer periphery thereof toward a center thereof.
9. The optical reflection element of claim 2 , wherein
the separation groove is made deeper from a center thereof toward an outer periphery thereof.