Variable optical attenuator

• US 6,137,941 A
• Filed: 09/03/1998
• Issued: 10/24/2000
• Est. Priority Date: 09/03/1998
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Robinson, Kevin Cyrus
• Primary Examiner(s): NGO, HUNG NHAT
• Application Number:
  US09/146,446
• Time in Patent Office: 782 Days
• Field of Search: 385/140, 385/25, 385/33, 385/34, 385/35, 385/18, 385/23
• US Class Current: 385/140
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Abstract

A variable optical attenuator includes a lens, first and second optical waveguides, and a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides. The semiconductor micro-electro-mechanical device may be, for example, a digital micromirror device or a silicon micro-electro-mechanical system. The device has a reflecting surface. The reflecting surface has a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide. The reflecting surface has a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions. By pivoting the reflecting surface about 0.35 degrees or less from the normal position, 40 dB of attenuation are obtained relative to the normal position. The optical attenuator can achieve about 25 dB of attenuation using a 5 Volt power supply.

Claims

1. A variable optical attenuator, comprising:

a lens;

first and second optical waveguides; and

a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface,

the reflecting surface having a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide,

the reflecting surface having a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions,

wherein the first and second optical waveguides are positioned so that 40 dB of attenuation are produced by pivoting the reflecting surface about 0.35 degrees or less from the normal position.

2. A variable optical attenuator according to claim 1, wherein the semiconductor micro-electro-mechanical device is one of the group consisting of a digital micromirror device and a silicon micro-electro-mechanical system.

3. A variable optical attenuator according to claim 1, wherein the semiconductor micro-electro-mechanical device is a digital micromirror device (DMD) including one of the group consisting of a piezoelectric element and an electrostatic element, for pivoting the reflecting surface.

4. A variable optical attenuator, comprising:

a lens;

first and second optical waveguides; and

a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface,

the reflecting surface having a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide,

the reflecting surface having a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions,

wherein the first and second optical waveguides are positioned so that 20 dB of attenuation are produced by pivoting the reflecting surface about 0.1 degree from the normal position.

5. A variable optical attenuator, comprising:

a lens;

first and second optical waveguides; and

a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface,

the reflecting surface having a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide,

the reflecting surface having a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions,

wherein the micro-electro-mechanical device pivots the reflecting surface sufficiently to produce 25 dB of attenuation using a power source of about five volts.

6. A variable optical attenuator, comprising:

a lens;

means for transmitting light to the lens

means for receiving light from the lens;

a reflecting surface; and

pivoting means for pivotally supporting the reflecting surface, and for pivoting the reflecting surface to;

a normal position in which light from the transmitting means reflects off of the reflecting surface and passes through the lens into the receiving means, and

a plurality of respectively different attenuating positions in which light from the transmitting means reflects off of the reflecting surface and passes through the lens, but an amount of light entering the receiving means is attenuated by respectively different amounts corresponding to the respectively different positions,

wherein, the first and second optical waveguides are positionable in one of the group consisting of;

a first position in which 40 dB of attenuation are produced by pivoting the reflecting surface about 0.35 degrees or less from the normal position, and

a second position in which 20 dB of attenuation are produced by pivoting the reflecting surface about 0.1 degree from the normal position.

7. A variable optical attenuator according to claim 6, wherein the pivoting means is a silicon micro-electro-mechanical device.

8. A variable optical attenuator according to claim 6, wherein the transmitting and receiving means are optical fibers.

9. A variable optical attenuator, comprising:

a lens;

first and second optical waveguides;

a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface,

the reflecting surface having a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide,

the reflecting surface having an attenuating position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated; and

a controller that controls a duty cycle of switching the reflecting surface between the reflecting position and the attenuating position, thereby to control an average amount of light entering the second waveguide.

10. A variable optical attenuator according to claim 9, wherein the semiconductor micro-electro-mechanical device is a digital micromirror device.

11. A method for controlling a beam of light, comprising the steps of:

(a) providing a lens, first and second optical waveguides, and a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface;

(b) pivoting the reflecting surface to a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide; and

(c) pivoting the reflecting surface to a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions, including pivoting the reflecting surface about 0.35 degrees or less from the normal position to achieve 40 dB of attenuation relative to the normal position.

12. A method for controlling a beam of light, comprising the steps of:

(a) providing a lens, first and second optical waveguides, and a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface;

(b) pivoting the reflecting surface to a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide; and

(c) pivoting the reflecting surface to a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions, including pivoting the reflecting surface about 0.1 degree or less from the normal position to achieve 20 dB of attenuation relative to the normal position.

13. A method for controlling a beam of light, comprising the steps of:

(a) providing a lens, first and second optical waveguides, and a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides, the device having a reflecting surface;

(b) pivoting the reflecting surface to a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide; and

(c) pivoting the reflecting surface to a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions, including applying a potential of about five volts to the semiconductor micro-electro-mechanical device to pivot the reflecting surface sufficiently to produce 25 dB of attenuation.