Directly modulated laser optical transmission system
First Claim
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1. An optical transmitter for generating a modulated optical signal for transmission over a dispersive fiber optic link to a remote receiver comprising:
- an input for receiving a broadband analog radio frequency signal input;
a semiconductor external cavity laser for producing an optical signal to be transmitted over an optical fiber;
a modulation circuit for directly modulating the laser with the analog signal, including a predistortion circuit for reducing the distortion in the signal present at the receiver end of the fiber optic link; and
a spectral shaping device connected to an output of the laser for adjusting an optical spectrum so that a power output of the laser is below a stimulated Brillouin scattering threshold of the fiber optic link.
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Abstract
An optical transmitter for generating a modulated optical signal for transmission over dispersive fiber optic links in which a broadband analog radio frequency signal input is applied to a modulation circuit for directly modulating a semiconductor laser with the analog signal input. The transmitter may further include a temperature sensor in proximity to the laser and a negative feedback control circuit coupled to the temperature sensor for adjusting the temperature of the laser in response to an output characteristic of the laser, such as linearity.
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Citations
29 Claims
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1. An optical transmitter for generating a modulated optical signal for transmission over a dispersive fiber optic link to a remote receiver comprising:
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an input for receiving a broadband analog radio frequency signal input; a semiconductor external cavity laser for producing an optical signal to be transmitted over an optical fiber; a modulation circuit for directly modulating the laser with the analog signal, including a predistortion circuit for reducing the distortion in the signal present at the receiver end of the fiber optic link; and a spectral shaping device connected to an output of the laser for adjusting an optical spectrum so that a power output of the laser is below a stimulated Brillouin scattering threshold of the fiber optic link. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An optical transmitter for generating a modulated optical signal for transmission over a dispersive fiber optic link to a remote receiver comprising:
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an input for receiving a broadband analog radio frequency signal input; a semiconductor laser for producing an optical signal to be transmitted over an optical fiber; a modulation circuit for directly modulating the laser with the analog signal; a temperature sensor in proximity to the laser for monitoring the temperature of the laser, and a control circuit coupled to the temperature sensor for adjusting the temperature of the laser in response to an optical output characteristic of the laser. - View Dependent Claims (17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29)
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23. An optical transmitter for generating a modulated optical signal for transmission over a dispersive fiber optic link to a remote receiver comprising:
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an input for receiving a broadband analog radio frequency signal input; a semiconductor laser for producing an optical signal to be transmitted over an optical fiber; a modulation circuit for directly modulating the laser with the analog signal; and output spectral shaping adjustment means connected to the output of the semiconductor laser for adjusting the average output power of the optical carrier signal so that the power is below that of the stimulated Brillouin scattering threshold of the dispersive fiber optic link.
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Specification