Tunable Fabry Perot microelectromechanical resonator adapted for optical filters and lasers with reduced optical power-dependent tuning

• US 6,580,516 B1
• Filed: 11/01/2000
• Issued: 06/17/2003
• Est. Priority Date: 11/01/2000
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Sorin, Wayne V., Tucker, Rodney S.
• Primary Examiner(s): Turner; Samuel A.
• Assistant Examiner(s): Lyons; Michael A.
• Application Number:
  US09/703,546
• Time in Patent Office: 958 Days
• Field of Search: 356/519,454
• US Class Current: 356/519
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: H01S 5/141 using a wavelength selective device, e.g. a grating or etalon H01S5/146 takes precedence

Abstract

A tunable optical resonator constructed from a fixed mirror and a moveable mirror. The fixed mirror is attached to a substrate having a first electrically conducting surface. A support member having the moveable mirror supported thereon and a second electrically conducting surface is suspended above the substrate such that the moveable mirror is separated from the fixed mirror. A light output port transmits a light signal of a wavelength determined by the distance between the fixed and moveable mirrors. An optical circuit measures the power level of the light signal and generates an electrical signal that depends on the measured power level. A frequency adjustment circuit, responsive to the electrical signal and a tuning voltage, applies an electrical potential between the first and second electrically conducting surfaces. The electrical potential causes the distance to remain at a distance determined by the tuning voltage independent of the power level for power levels less than a predetermined power level. The resonator can be used to construct a laser by incorporating an active layer for amplifying light trapped in the cavity. The resonator can also be used a tunable optical filter by including an input port for receiving a light signal that is to be filtered. In one embodiment of the invention, a feedback circuit consisting of an optical coupler, photodiode, amplifier, and signal adder is used to generate the potential between the first and second electrically conducting surfaces.

Claims

1. A tunable optical resonator comprising:

a fixed mirror attached to a substrate having a first electrically conducting surface;

a support member having a moveable mirror supported thereon, said support member having a second electrically conducting surface, said support member being suspended above said substrate such that said moveable mirror is separated from said fixed mirror by a distance;

a light output port for transmitting a light signal of a wavelength determined by said distance, said transmitted light signal being characterized by a power level;

an optical circuit for measuring said power level of said light signal and for generating an electrical signal that depends on said measured power level; and

a frequency adjustment circuit, responsive to said electrical signal and a tuning voltage, for applying an electrical potential between said first and second electrically conducting surfaces, wherein said electrical potential causes said distance to remain at a distance determined by said tuning voltage independent of said power level for power levels less than a predetermined power level.

2. The optical resonator of claim 1 further comprising an active layer for amplifying light trapped in said cavity.

3. The optical resonator of claim 1 further comprising an input port for receiving a light signal that is reflected between said fixed and moveable mirrors.

4. The optical resonator of claim 1, wherein said optical circuit comprises an optical coupler and a light to electrical converter.

5. The optical resonator of claim 4 wherein said electrical converter is a photodiode.

6. The optical resonator of claim 1, wherein said frequency adjustment circuit comprises a non-inverting amplifier and adder, said electrical potential being proportional to V+BP, where V is said tuning voltage, P is said measured power, and B is a constant.

7. The optical resonator of claim 6, wherein B is a function of said tuning voltage.