# US 7,412,170 B1 · Broad temperature WDM transmitters and receivers for coarse wavelength division multiplexed (CWDM) fiber communication systems

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- Number: US 7,412,170 B1
- Document ID: US7412170B1
- Status: Granted
- Kind: B1
- Application number: 10/852,842
- Filed: 2004-05-24
- Granted: 2008-08-12
- Earliest claimed: 2003-05-29
- Assignees: Opticomp Corporation
- Inventors: Duane A. Louderback; Peter Guilfoyle
- Web page: https://patentgrep.com/patent/US7412170B1

## CPC

- H01S 5/423: {having a vertical cavity}
- H04J 14/02: Wavelength-division multiplex systems
- H01S 5/18308: {having a special structure for lateral current or light confinement}
- H01S 5/18319: {comprising a periodical structure in lateral directions}
- H01S 5/18366: {Membrane DBR, i.e. a movable DBR on top of the VCSEL}
- H01S 5/18386: {Details of the emission surface for influencing the near- or far-field, e.g. a grating on the surface}
- H01S 5/4087: {emitting more than one wavelength}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A wavelength division multiplexing (WDM) module for transmitting and/or receiving multiple signals simultaneously includes an array of vertical cavity surface emitting lasers (VCSELs) and/or photodetectors, respectively. In the transmitter case, different VCSELs are operated at different wavelengths that change depending on a value of a condition such as temperature and/or one or more other parameters. Multiple VCSELs are assigned to each channel of the WDM. The currently active VCSEL is switched to a different VCSEL assigned to a same channel and preferably having an operating wavelength that is closer to the signal wavelength at the current measured or estimated temperature and/or other parameter value. Multiple photodetectors are assigned to each channel of the WDM, and currently active detector is switched to the second detector within the same channel. A tuning layer and a resonant waveguide grating coupler are preferably integrated into the resonant structure of the VCSEL array and wavelength specific detector array.

## Claims

### Claim 1

A wavelength division multiplexing (WDM) module for receiving multiple signals simultaneously in CWDM or DWDM optical fiber communication system, comprising:
an array of photodetectors including multiple photodetectors assigned to a single channel and having different ranges of operating wavelengths; and
control electronics for switching a currently active photodetector to a second photodetector within the channel operating at a preferred wavelength compared to that of the active photodetector, wherein the switching is based on a determined value of a parameter of the WDM module.

### Claim 2 (depends on 1)

The WDM module of claim 1, wherein the determined value comprises a measured value of said parameter of the WDM module.

### Claim 3 (depends on 2)

The WDM module of claim 2, wherein the parameter comprises temperature.

### Claim 4 (depends on 3)

The WDM module of claim 3, wherein thermal compensation is provided by adding redundant photodetectors for each channel, the redundant photodetectors operating at different wavelengths.

### Claim 5 (depends on 1)

The WDM module of claim 1, wherein the control electronics comprise a switch configured to select an active photodetector based on an input signal.

### Claim 6 (depends on 1)

The WDM module of claim 1, further comprising a waveguide and wavelength specific photodetector array multiplexed into the waveguide.

### Claim 7 (depends on 6)

The WDM module of claim 6, further comprising a grating coupler providing optical coupling of the waveguide and detectors.

### Claim 8 (depends on 1)

The WDM module of claim 1, further comprising a tuning layer within a resonant structure of the photodetector array.

### Claim 9 (depends on 1)

The WDM module of claim 1, further comprising a digital signal processing (DSP) unit which allows calibration of wavelengths as a function of temperature, stores them in memory, and switches active wavelength specific detectors within specified boundaries of operating channels depending on the temperature.

### Claim 10

A wavelength insensitive wavelength division multiplexing (WDM) module capable of transmitting and receiving multiple signals simultaneously in a CWDM or DWDM optical fiber bi-directional data communication system, comprising:
an array of vertical cavity surface emitting lasers (VCSELs) including multiple VCSELs assigned to a single channel and having different operating wavelengths; and
control electronics for switching a currently active VCSEL to a second VCSEL within the channel operating at a preferred wavelength compared to that of the active VCSEL, wherein this switching is being based on a determined value of a parameter of the WDM module,
an array of photodetectors including multiple photodetectors assigned to the same or a different single channel and having different ranges of operating wavelengths;
control electronics for switching a currently active photodetector to a second photodetector within the channel operating at a preferred wavelength range compared to that of the active photodetector, wherein the switching is being based on the same or a different determined value of the same or a different parameter of the WDM module.

### Claim 11 (depends on 10)

The WDM module of claim 10, wherein the determined value or values comprise a measured value or measured values of said parameter or parameters of the WDM module.

### Claim 12 (depends on 11)

The WDM module of claim 11, wherein the parameter or parameters comprise temperature.

### Claim 13 (depends on 12)

The WDM module of claim 12, wherein thermal compensation is provided by adding redundant photodetectors, the redundant photodetectors operating at different wavelengths.

### Claim 14 (depends on 12)

The WDM module of claim 12, wherein thermal compensation is provided by adding redundant VCSELs, the redundant VCSELs operating at different wavelengths.

### Claim 15 (depends on 11)

The WDM module of claim 11, wherein the control electronics comprise a switch configured to select the active VCSEL based on an input signal.

### Claim 16 (depends on 11)

The WDM module of claim 11, wherein the control electronics comprise a switch configured to select the active photodetector based on an input signal.

### Claim 17 (depends on 16)

The WDM module of claim 16, wherein the same or a different switch of the control electronics is configured to select the active VCSEL based on an input signal.

### Claim 18 (depends on 11)

The module of claim 11, further comprising a waveguide and wavelength specific
VCSEL array multiplexed into the waveguide.

### Claim 19 (depends on 18)

The module of claim 18, further containing a grating coupler providing optical coupling of the VCSELs and the waveguide.

### Claim 20 (depends on 11)

The module of claim 11, further comprising a waveguide and wavelength specific
photodetector array multiplexed into the waveguide.

### Claim 21 (depends on 20)

The module of claim 20, further comprising a grating coupler providing optical coupling of the waveguide and detectors.

### Claim 22 (depends on 11)

The module of claim 11, further comprising a tuning layer within the resonant structure of the VCSEL array.

### Claim 23 (depends on 11)

The module of claim 11, further comprising a tuning layer within the resonant structure of the photodetector array.

### Claim 24 (depends on 11)

The module of claim 11, further comprising a digital signal processing (DSP) unit which allows calibration of wavelengths as a function of temperature, stores them in memory, and switches active wavelength specific VCSELs and detectors within specified boundaries of operating channels depending on the temperature.