A photonic package includes a housing having a semiconductor light source disposed within the housing. The semiconductor light source has a first output and a second output. A reflective surface is disposed inside the housing to reflect the second output from the semiconductor light source. A photodetector is also disposed within the housing and is adapted to indirectly receive the second output of the semiconductor light source reflected off the reflective surface. As a result, interior surface of a housing of an optical transponder may be utilized to provide reflected light to a photodetector to monitor the semiconductor light source.
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0. 17. A method of monitoring a semiconductor light source substantially enclosed in a housing, the method comprising:
generating a light output signal from the semiconductor light source;
deflecting the light output signal from a back facet of the semiconductor light source toward an interior surface of the housing;
reflecting the light output signal from the interior surface toward a photodetector; and
receiving, at the photodetector, the light output signal reflected from the interior surface.
1. A photonic package comprising:
a housing;
a semiconductor light source disposed within the housing, the semiconductor light source having a first output and a second output;
a first reflective surface disposed inside the housing selected from one of a side wall of the housing and an interior surface of a cover of the housing to reflect said second output;
a second reflective surface to deflect the second output to the first reflective surface; and
a photodetector disposed within the housing adapted to indirectly receive said second output of the semiconductor light source reflected off said first reflective surface.
16. A photonic package comprising:
a housing;
a semiconductor light source disposed within the housing, the semiconductor light source having a first output and a second output;
a first reflective surface disposed inside the housing to reflect said second output;
a second reflective surface to deflect the second output to the first reflective surface, at least one of said first and said second reflective surfaces is selected from one of a side wall of the housing and an interior surface of a cover of the housing; and
a photodetector disposed within the housing adapted to indirectly receive said second output of the semiconductor light source reflected off said first reflective surface.
12. A method for forming a photonic package comprising:
providing a semiconductor light source to provide a first and a second output;
providing a first reflective surface to reflect the second output of the semiconductor light source, wherein said providing of a first reflective surface comprises providing a reflective interior surface to a housing of the photonic package;
providing a second reflective surface and disposing said second reflective surface in a manner such that said second reflective surface reflects said second output of the semiconductor light source to said reflective interior surface of the housing, for reflection to said a photodetector; and
adapting a said photodetector to indirectly receive the second output of the semiconductor light source reflected from the interior surface.
3. The photonic package of
4. The photonic package of
5. The photonic package of
6. The photonic package of
7. The photonic package of
10. The photonic package of
11. The photonic package of
13. The method of
14. The method of
15. The photonic package of
0. 18. The method of claim 17, wherein said deflecting comprises deflecting the light output signal toward an interior surface selected from one of a side wall of the housing or an interior surface of a cover of the housing.
0. 19. The method of claim 18, wherein the selected interior surface comprises a reflective surface.
0. 20. The method of claim 17, wherein said deflecting comprises deflecting the light output signal toward an interior surface having a reflective surface.
0. 21. The method of claim 20, wherein the reflective surface comprises a silicon mirror.
0. 22. The method of claim 20, wherein the reflective surface comprises a reflective sheet.
0. 23. The method of claim 20, wherein the reflective surface comprises a dielectric coating surface.
0. 24. The method of claim 17, further comprising:
generating an electrical signal at the photodetector in response to said receiving the light output signal.
0. 25. The method of claim 24, further comprising:
comparing, by a processor, the electrical signal to characterization data to facilitate calibration of the received light output signal by the photodetector.
0. 26. The method of claim 25, further comprising:
facilitating, by the processor, an adjustment of a bias voltage of the photodetector in response to said comparing.
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In order to describe the invention, references will be made to an exemplary area 110 & 350 (an area around the semiconductor light source).
Illustrated also in
For example, the photodetector 205 may be a p-i-n junction photodiode, where spectral responsivity may be expressed as
In Equation 1, I is amperes of current generated by the photodetector 205, and L is power of incident light, the reflected light 210, measured in watts. R is responsivity in units of amperes per watt. Furthermore, external quantum efficiency of a photodiode is its capability to convert light energy to electrical energy (i.e., electrical signals), and can be expressed as a relation to responsivity as
where EQE (λ) is external quantum efficiency as function of wavelength, I is photocurrent (output current—dark output current) as function wavelength, h is Planck's constant, c is velocity of light, Φ is input radiant flux (power), n is index of refraction of air, e is elementary charge, and λ is wavelength of light in units of nanometers. Accordingly, the Equation 1 and Equation 2 can be utilized to form the relationship
where R and λ, as defined earlier, are responsivity in units of amperes per watt and wavelength of light in units of nanometers, respectively.
The electrical signals may be provided to the processor wherein the electrical signals may be compared to characterization data. The characterization data may relate electrical signals from the photodetector 205 produced by reflected 210 light received by the photodetector 205 of the first output 201 of the light source 101. For example, referring to
As a result, a photodetector can be adapted to receive light reflected from a surface of a component disposed at the back of the semiconductor light source, housed inside a densely populated housing of an optical transponder, thereby advantageously monitoring a semiconductor light source from locations other than those that are directly behind the semiconductor light source (i.e., the photodetector is not required to be in direct path of the back output of the semiconductor light source).
In one embodiment, the interior surface of the cover 303 may have a coating to help facilitate cover reflected light 305, such as, but not limited to, paint having a pigment of titanium dioxide (i.e., white paint).I
In one embodiment, the reflective mirror surface 301 may be a highly polished silicon mirror or a dielectric coating. In alternative embodiments, it may be a reflective sheet or stripe.
Alternatively, in one embodiment, the reflective mirror surface 301 may be disposed in such a manner as to reflect the second output 202 from the back facet 103 of the light source 101 to one or more other secondary reflective surfaces, such as, but not limited to, a side wall of horsing (not shown). For these embodiments, the photodetector will be adapted accordingly in a coordinated manner to receive light reflected from the alternate secondary reflective wall by positioning the receiving window of the photodetector to face the alternate secondary reflective wall.
As a result, alternate interior surfaces of a housing of an optical transponder may be utilized to provide reflected light to a photodetector adapted to receive the reflected light.
Thus, it can be seen from the above descriptions, a novel method and apparatus for indirect monitoring of a light source by a photodetector, has been described.
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Thus, the description is to be regarded as illustrative instead of restrictive on the invention.
Booman, Richard A., Ohm, David R.
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Mar 01 2002 | OHM, DAVID R | NETWORK ELEMENTS, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 025611 | /0264 | |
Mar 01 2002 | BOOMAN, RICHARD A | NETWORK ELEMENTS, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 025611 | /0264 | |
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Sep 08 2005 | TriQuint Semiconductor, Inc | Null Networks LLC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 025611 | /0449 | |
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