Abstract: The invention relates to a feedback loop for a laser diode driving circuit for ensuring that the laser diode generates optical power at a constant safe level. The feedback loop includes a monitor diode, which generates a monitor current Imon, and a set resistance for generating a set voltage based on the monitor current and the set resistance. The set voltage is compared with a reference voltage in an operational amplifier, which generates a control signal for controlling the laser diode current source. The laser diode current source dictates the amount of bias current transmitted to the laser diode. Safety features, in the form of voltage comparators, are provided to ensure that: a) the feedback loop is closed, i.e. Imon is not too low; b) the optical power is not above standard safety threshold, i.e. Imon is not too high; and c) the monitor diode voltage is sufficient to provide specified optical power to electrical power conversion.

Abstract: A method and apparatus are provided to ensure that laser optical power does not exceed a “safe” level in a DC coupled open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number N of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks, and the corresponding low duty cycle signal is generated by a safety pulse generator in the safety channel.

Abstract: The invention relates to a feedback loop for a laser diode driving circuit for ensuring that the laser diode generates optical power at a constant safe level. The feedback loop includes a monitor diode, which generates a monitor current Imon, and a set resistance for generating a set voltage based on the monitor current and the set resistance. The set voltage is compared with a reference voltage in an operational amplifier, which generates a control signal for controlling the laser diode current source. The laser diode current source dictates the amount of bias current transmitted to the laser diode. Safety features, in the form of voltage comparators, are provided to ensure that: a) the feedback loop is closed, i.e. Imon is not too low; b) the optical power is not above standard safety threshold, i.e. Imon is not too high; and c) the monitor diode voltage is sufficient to provide specified optical power to electrical power conversion.

Abstract: A method and apparatus are provided to ensure that laser optical power does not exceed a “safe” level in an open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks.

Abstract: A method and apparatus are provided to ensure that laser optical power does not exceed a “safe” level in a DC coupled open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number N of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks, and the corresponding low duty cycle signal is generated by a safety pulse generator in the safety channel.

Abstract: An improved laser diode driving circuit is disclosed which includes a current source, an operational amplifier, a light sensing device, a current mirror, and a constant current source. The current source is coupled to the laser diode for biasing the laser diode. The operational amplifier has an output coupled to the current source for driving the current source. The operational amplifier includes a first and a second input. The first input is coupled to a reference voltage. The second input receives a feedback signal. The light sensing device is coupled to a first supply voltage for detecting a portion of an optical power output from the laser. The light sensing device generates a monitor current proportional to the detected optical power output. The current mirror is coupled to the light sensing device and the second input of the operational amplifier. The current mirror receives the monitor current and generates a mirror current which is substantially equal to the monitor current.