# US 9,882,651 B2 · Methods, circuits and optical cable assemblies for optical transmission of high-speed data and low-speed data

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,882,651 B2
- Document ID: US9882651B2
- Status: Granted
- Kind: B2
- Application number: 15/063,617
- Filed: 2016-03-08
- Published: 2016-06-30
- Granted: 2018-01-30
- Earliest claimed: 2013-09-13
- Assignees: Corning Optical Communications LLC
- Applicants: Corning Optical Communications LLC
- Inventors: Richard Clayton Walker
- Web page: https://patentgrep.com/patent/US9882651B2

## CPC

- H04B 10/564: Power control
- H04B 10/503: {Laser transmitters}
- H04B 10/516: Details of coding or modulation
- H04B 10/5161: {Combination of different modulation schemes}
- H04B 10/541: {Digital intensity or amplitude modulation}
- H04B 10/66: Non-coherent receivers, e.g. using direct detection
- H04B 2210/074: using a superposed, over-modulated signal
- H04B: TRANSMISSION

## Abstract

Methods, circuits and active optical cable assemblies for simultaneous transmission of low-speed optical data and high-speed optical data over an optical fiber link are disclosed. In one embodiment, a method of optical communication includes controlling a laser such that an output of the laser transmits high-speed optical data at a first bit rate, and modulating an amplitude of the output of the laser such that the laser transmits low-speed optical data at a second bit rate simultaneously with the high-speed optical data. In another embodiment, a circuit for providing optical communication includes a laser and a laser driver circuit that digitally modulates an output of the laser to transmit high-speed optical data at a first bit rate. The circuit further includes an amplitude modulation circuit that modulates an amplitude of the laser to transmit low-speed optical data at a second bit rate simultaneously with the high-speed optical data.

## Claims

### Claim 1

A method of optical communication, the method comprising:
controlling a laser such that an output of the laser transmits high-speed optical data at a first bit rate; and
modulating an amplitude of the output of the laser such that the laser transmits low-speed optical data at a second bit rate simultaneously with the high-speed optical data, wherein the first bit rate is higher than the second bit rate, wherein
the laser is controlled by applying a laser driver current ILD to the laser, and
the laser driver current ILD is modulated by adding and removing a drive current ID to and from a bias current IB, and adding and removing a delta current IΔto and from the drive current ID.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving the output of the laser; and
simultaneously detecting the high-speed optical data and the low-speed optical data.

### Claim 3 (depends on 1)

The method of claim 1, further comprising converting the high-speed optical data into high-speed electrical data and the low-speed optical data into low-speed electrical data.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the high-speed optical data is defined by a high optical power value PH that is above a threshold and a low optical power value PL that is below the threshold; and
the amplitude of the output of the laser is modulated at the second bit rate such that:
the high optical power value PH is either a first high optical power value PH1 or a second high optical power value PH2 that is greater than the first high optical power value PH1; and
the low optical power value PL is either a first low optical power value PL1 or a second low optical power value PL2 that is less than the first low optical power value PL1.

### Claim 5 (depends on 4)

The method of claim 4, wherein:
a logical one of the high-speed optical data is provided by the high optical power value PH, and a logical zero of the high-speed optical data is provided by the low optical power value PL; and
a logical one of the low-speed optical data is provided by the second high optical power value PH2 or the second low optical power value PL2, and a logical zero of the low-speed optical data is provided by the first high optical power value PH1 or the first low optical power value PL1.

### Claim 6 (depends on 5)

The method of claim 5, further comprising:
receiving the output of the laser; and
converting the output of the laser into an input electrical signal comprising a high-speed electrical data component and low-speed electrical data component corresponding to the high-speed optical data and the low-speed optical data, respectively.

### Claim 7 (depends on 6)

The method of claim 6, further comprising decoding the low-speed electrical data component by applying a low-pass filter to the input electrical signal to filter out the high-speed electrical data component, and detecting logical ones and logical zeros of the low-speed electrical data component by comparing the low-pass filtered input electrical signal to an average voltage of the low-pass filtered input electrical signal.

### Claim 8 (depends on 1)

The method of claim 1, wherein:
a logical one of the high-speed optical data is provided by adding the drive current ID to the bias current IB applied to the laser, and a logical zero of the high-speed optical data is provided by removing the drive current ID from the bias current IB applied to the laser; and
a logical one of the low-speed optical data is provided by adding the delta current IΔto the drive current ID, and a logical zero of the low-speed optical data is provided by removing the delta current I66 from the drive current ID.

### Claim 9

A circuit for providing optical communication comprising:
a laser; and
a laser driver circuit that digitally modulates an output of the laser to transmit high-speed optical data at a first bit rate; and
an amplitude modulation circuit that modulates an amplitude of the laser to transmit low- speed optical data at a second bit rate simultaneously with the high-speed optical data, wherein the first bit rate is higher than the second bit rate, wherein
the laser driver circuit and the amplitude modulation circuit applies a laser driver current ILD to the laser, and
the laser driver circuit is configured to modulate the laser driver current ILD by adding and removing a drive current ID to and from a bias current IB to produce the high-speed optical data, and by adding and removing a delta current IΔto and from the drive current ID to produce the low-speed optical data.

### Claim 10 (depends on 9)

The circuit of claim 9, further comprising:
a receiver circuit for converting the output of the laser into an input electrical signal, wherein the receiver circuit generates high-speed electrical data from the input electrical signal; and
an amplitude detector circuit electrically coupled to the receiver circuit for detecting amplitude variations of the output of the laser based on the input electrical signal, wherein the amplitude detector detects low-speed electrical data based on the detected amplitude variations.

### Claim 11 (depends on 10)

The circuit of claim 10, wherein the receiver circuit comprises a photodiode and a transimpedance amplifier.

### Claim 12 (depends on 9)

The circuit of claim 9, wherein:
the laser driver circuit controls the laser such that the high-speed optical data provided by the output of the laser is defined by a high optical power value PH that is above a threshold and a low optical power value PL that is below the threshold; and
the amplitude modulation circuit modulates the amplitude of the output of the laser at the second bit rate such that:
the high optical power value PH is either a first high optical power value PH1 or a second high optical power value PH2 that is greater than the first high optical power value PH1; and
the low optical power value PL is either a first low optical power value PL1 or a second low optical power value PL2 that is less than the first low optical power value PL1.

### Claim 13 (depends on 12)

The circuit of claim 12, wherein:
a logical one of the high-speed optical data is provided by the high optical power value PH, and a logical zero of the high-speed optical data is provided by the low optical power value PL; and
a logical one of the low-speed optical data is provided by the second high optical power value PH2 or the second low optical power value PL2, and a logical zero of the low-speed optical data is provide by the first high optical power value PH1 or the first low optical power value PL1.

### Claim 14 (depends on 13)

The circuit of claim 13, further comprising:
a receiver circuit for converting the output of the laser into an input electrical signal, wherein the input electrical signal has a digitally modulated high-speed electrical data component corresponding to the high-speed optical data, and an amplitude-modulated low-speed electrical data component corresponding to amplitude variations of the low-speed optical data; and
an amplitude detector circuit comprising:
a low-pass filter circuit operable to filter out the digitally modulated high-speed electrical data component of the input electrical signal such that the filtered input electrical signal switches between a first voltage VMIN corresponding to the first high optical power value PH1 and a second voltage VMAX corresponding to the second high optical power value PH2; and
a comparator circuit to detect the amplitude-modulated low-speed electrical data component by comparing the filtered input electrical signal to a reference voltage, wherein the comparator circuit generates a logical one when the second voltage VMAX greater than the reference voltage is present and a logical zero when the first voltage VMIN less than the reference voltage is present.

### Claim 15 (depends on 9)

The circuit of claim 9, wherein:
a logical one of the high-speed optical data is provided when the laser driver circuit adds the drive current ID to the bias current IB applied to the laser, and a logical zero of the high-speed optical data is provided when the laser driver circuit removes the drive current ID from the bias current IB applied to the laser; and
a logical one of the low-speed optical data is provided when the laser driver circuit adds the delta current IΔto the drive current ID, and a logical zero of the low-speed optical data is provided when the laser driver circuit removes the delta current IΔfrom the drive current ID.

### Claim 16 (depends on 15)

The circuit of claim 15, wherein the circuit comprises a bias current source that provides the bias current IB, a drive current source that provides the drive current ID, and a delta current source that provides the delta current IΔ.

### Claim 17

An active optical cable assembly comprising:
an optical fiber having a first end;
a first electrical connector at the first end of the optical fiber;
a laser disposed within the first electrical connector;
a laser driver circuit within the first electrical connector that digitally modulates an output of the laser to transmit high-speed optical data at a first bit rate over the optical fiber in accordance with a high-speed data stream received at the first electrical connector; and
an amplitude modulation circuit within the first electrical connector that modulates an amplitude of the laser to transmit low-speed optical data at a second bit rate simultaneously with the high-speed optical data over the optical fiber in accordance with a low-speed data stream received at the first electrical connector, wherein the first bit rate is higher than the second bit rate,
wherein:
the laser driver circuit controls the laser such that the high-speed optical data provided by the output of the laser is defined by a high optical power value PH that is above a threshold and a low optical power value PL that is below the threshold; and
the amplitude modulation circuit modulates the amplitude of the output of the laser at the second bit rate such that:
the high optical power value PH is either a first high optical power value PH1 or a second high optical power value PH2 that is greater than the first high optical power value PH1; and
the low optical power value PL is either a first low optical power value PL1 or a second low optical power value PL2 that is less than the first low optical power value PL1.

### Claim 18 (depends on 17)

The active optical cable assembly of claim 17, wherein:
a logical one of the high-speed optical data is provided by the high optical power value PH, and a logical zero of the high-speed optical data is provided by the low optical power value PL; and
a logical one of the low-speed optical data is provided by the second high optical power value PH2 or the second low optical power value PL2, and a logical zero of the low-speed optical data is provide by the first high optical power value PH1 or the first low optical power value PL1.

### Claim 19 (depends on 18)

The active optical cable of claim 18, further comprising:
a second electrical connector at a second end of the optical fiber;
a receiver circuit within the second electrical connector for receiving the output of the laser from the optical fiber, and converting the output of the laser into an input electrical signal, wherein the input electrical signal has a digitally modulated high-speed electrical data component corresponding to the high-speed optical data, and an amplitude-modulated low-speed electrical data component corresponding to amplitude variations of the low-speed optical data; and
an amplitude detector circuit within the second electrical connector, the amplitude detector circuit comprising:
a low-pass filter circuit operable to filter out the digitally modulated high-speed electrical data component of the input electrical signal such that the filtered input electrical signal switches between a first voltage VMIN corresponding to the first high optical power value PH1 and a second voltage VMAX corresponding to the second high optical power value PH2; and
a comparator circuit to detect the amplitude-modulated low-speed electrical data component by comparing the filtered input electrical signal to a reference voltage, wherein the comparator circuit generates a logical one when the second voltage VMAX greater than the reference voltage is present and a logical zero when the first voltage VMIN less than the reference voltage is present.

### Claim 20 (depends on 17)

The active optical cable assembly of claim 17, wherein the laser driver circuit is configured to add and remove a drive current ID to and from a bias current IB to produce the high-speed optical data, and add and remove a delta current IΔto and from the drive current ID to produce the low-speed optical data.