Method for correcting for dark current variation in TEC cooled photodiodes
AssigneeViavi Solutions Inc.
InventorsChris Wagner, James Kirby Goulet
Life of this patent
Estimating the term…
Abstract
An optical power meter including a photodiode having a surface for receiving a beam of light, a thermo-electric cooler for maintaining the photodiode at a predetermined temperature, and a current monitor for measuring a drive current passing through the thermo-electric cooler allows dark current drift arising from a varying thermal gradient across the active region of the photodiode to be corrected, thus improving stability of the optical power meter. More specifically, by monitoring the TEC drive current, and applying a correction factor to the optical power readings, the stability of optical power readings is improved by an order of magnitude.
Claims16
A method of determining an optical power measurement using an optical power meter including a photodiode with a thermo-electric cooler (TEC) comprising:
- determining an initial dark current measurement of the photodiode, and an initial drive current of the TEC;
- measuring a power measurement of an optical beam;
- measuring a current drive current of the TEC;
- and
- calculating a corrected optical power measurement based on the initial dark current of the photodiode and on a difference between the initial drive current of the TEC and the current drive current of the TEC.
An apparatus comprising:
- a photodiode having a surface for receiving a beam of light, the photodiode to generate a current dependent upon an optical power of the beam of light;
- a thermo-electric cooler to maintain the photodiode at a predetermined temperature;
- a current monitor to measure a drive current passing through the thermo-electric cooler;
- and
- a controller to calculate the optical power of the beam of light, the controller including a non-transitory storage medium having instructions stored thereon to cause the controller to determine a correction factor based upon at least one current measured by the current monitor, wherein the optical power of the beam of light is dependent upon the correction factor, and
- wherein the instructions to cause the controller to determine the correction factor are to cause the controller to determine a difference between a second drive current reading of drive current passing through the thermo-electric cooler and a first drive current reading of drive current passing through the thermo-electric cooler, the first drive current reading obtained concurrently with a photodiode dark current reading and the second drive current reading obtained concurrently with a first optical power reading, each of the first and second drive current readings being measured with the current monitor.
An optical power meter comprising:
- a photodiode for measuring an optical power of a beam of light, the photodiode having an initial dark current;
- a thermo-electric cooler (TEC) for maintaining the photodiode at a predetermined temperature, the TEC having an initial drive current;
- a current meter for measuring a current drive current for the TEC;
- and
- a controller for calculating a corrected optical power reading based on the initial dark current and a difference between the initial drive current and the current drive current,
- wherein the controller includes a non-transitory storage medium having stored thereon a predetermined relationship between drive current of the thermo-electric cooler and dark current of the photodiode, and wherein the corrected optical power reading is based on the predetermined relationship.
A method of determining an optical power of a beam of light with a photodiode cooled by a thermo-electric cooler, comprising:
- measuring a dark current of the photodiode and a first drive current of the thermo-electric cooler;
- measuring a current of the photodiode when the beam of light is incident thereon and measuring a second drive current of the thermo-electric cooler;
- and
- calculating the optical power of the beam of light using the current of the photodiode and a correction factor, the correction factor using a predetermined relationship between drive current of the thermo-electric cooler and dark current of the photodiode.
Dependencies are inferred from the claim text.