Abstract: Methods to load control programs into an optical transceiver whose specifications follow the standards are disclosed. The standard transceiver, such as SFP transceiver and/or XFP transceiver, provides control terminals in addition to the serial interface to communicate with the host device. The control terminals are inactive when the transceiver is output of the host device. The loader to load the program utilizes those control terminals and the optical transceiver of the invention provides mechanisms to use those control terminals for downloading the program.

Abstract: Methods to load control programs into an optical transceiver whose specifications follow the standards are disclosed. The standard transceiver, such as SFP transceiver and/or XFP transceiver, provides control terminals in addition to the serial interface to communicate with the host device. The control terminals are inactive when the transceiver is output of the host device. The loader to load the program utilizes those control terminals and the optical transceiver of the invention provides mechanisms to use those control terminals for downloading the program.

Abstract: A method to control an LD (laser diode) is disclosed. The method compares the operating temperature of the LD with a transition temperature. When the former temperature exceeds the latter, the modulation current is set based on the bias current, which is independently determined by the APC loop. On the other hand, the operating temperature is less than the transition temperature; the modulation current is determined by the operating temperature.

Abstract: An effective algorithm for the CPU with a flash memory is disclosed to shorten a dead time to erase the flash memory and to write new data therein. The flash memory of the invention provides front and back blocks for the user data area. When the front block is filled, the back block is erased just after the front block is fully filled in advance to receive a new data next to be written.

Abstract: An optical receiver implemented with two electronic dispersion compensators (EDC) is disclosed. The optical receiver selects one of the EDC in an ordinary operation. Once there shaped signal compensated by the selected EDC is degraded due to irregular conditions of the optical transmission line, the optical transmitter and so on, the optical receiver reconfigures the tap coefficients of the unselected EDC and switches to the newly configured EDC after setting the tap coefficients for the new condition of the transmission line and the transmitter.

Abstract: A pluggable optical transceiver with a function not affecting the command status of the host system appeared in the internal bus, which is coupled with the command line within the transceiver, even when the transceiver is plugged in the host system. The optical transceiver provides a power supply circuit and a control unit. The power supply circuit, by receiving an external electric power, generates an internal electric power with a substantial time lag from a moment when the optical transceiver is plugged in the host system. The control unit communicates with the host system through the command line pulled up to the external electric power within the optical transceiver.

Abstract: The present invention provides an optical transmitter applicable to the WDM communication system. The optical transmitter includes a light-emitting device, an APC circuit and a processing unit. The processing unit, responding to a command TX_DISABL, which is sent from the control unit that communicates with the host controller, stops the optical output power of the transmitter by decreasing the reference to a preset value in step wise. Moreover, the processing unit, responding to a command ENABLE that is also sent from the control unit, starts the optical output by increasing the reference to another preset value in step wise.

Abstract: The present invention provides an optical transmitter applicable to the WDM communication system. The optical transmitter includes a light-emitting device, an APC circuit and a processing unit. The processing unit, responding to a command TX_DISABL, which is sent from the control unit that communicates with the host controller, stops the optical output power of the transmitter by decreasing the reference to a preset value in step wise. Moreover, the processing unit, responding to a command ENABLE that is also sent from the control unit, starts the optical output by increasing the reference to another preset value in step wise.

Abstract: An optical transmitter and a method to control the transmitter are disclosed, in which the optical output may be substantially maintained even in the inactive state of the input burst signal. The optical transmitter includes the APC feedback control and the detector that senses the active and inactive states of the input burst signal. When the transition to the inactive state is detected, the controller enters the second APC mode in which only the bias current is adjusted so as to maintain the optical output to be a preset value. The normal APC feedback control may be recovered after a preset period from the practical transition of the input burst signal from the inactive state to the active state.

Abstract: A method to control an LD (laser diode) is disclosed. The method compares the operating temperature of the LD with a transition temperature. When the former temperature exceeds the latter, the modulation current is set based on the bias current, which is independently determined by the APC loop. On the other hand, the operating temperature is less than the transition temperature; the modulation current is determined by the operating temperature.

Abstract: The present invention discloses an optical transmitter that provides a function to vary the rate of the increase of the bias and modulation currents and their practical values during the APC feedback loop is left unstable without prolonging this unstable period. The optical transmitter of the invention includes a controller configured to read initial parameters from the memory, to increase the bias and modulation currents in stepwise based on thus read initial parameters, and to begin the automatic feedback control to keep the optical output from the laser diode constant after the bias and modulation currents reach their temporarily target values.

Abstract: An effective algorithm for the CPU with a flash memory is disclosed to shorten a dead time to erase the flash memory and to write new data therein. The flash memory of the invention provides front and back blocks for the user data area. When the front block is filled, the back block is erased just after the front block is fully filled in advance to receive a new data next to be written.

Abstract: An optical transmitter and a method to control the transmitter are disclosed, in which the optical output may be substantially maintained even in the inactive state of the input burst signal. The optical transmitter includes the APC feedback control and the detector that senses the active and inactive states of the input burst signal. When the transition to the inactive state is detected, the controller enters the second APC mode in which only the bias current is adjusted so as to maintain the optical output to be a preset value. The normal APC feedback control may be recovered after a preset period from the practical transition of the input burst signal from the inactive state to the active state.

Abstract: The present invention is to provide a control algorithm of a thermo-electric cooler (TEC) for a laser diode (LD) where a rush current accompanied with the stepwise change of the target temperature of the TEC. First, the controller stops the TEC driver prior to the setting of the target temperature, and sets the present temperature of the LD. Subsequently, the controller gradually increases the reference temperature of the TEC in stepwise to the target temperature. Thus, the controller suppresses the rush current accompanied with the instantaneous increase of the reference temperature of the TEC.

Abstract: A pluggable optical transceiver is disclosed, in which the transceiver includes first and second circuit blocks. The first circuit block is powered by the first power supply in the host system via a first switch, while the second circuit block is powered by the second power supply also in the host system via a second switch. The first and second switches turn on in the same time even when the first and second power supplies in the host system become active sequentially with a time lag.

Abstract: The present invention is to provide a control algorithm of a thermo-electric cooler (TEC) for a laser diode (LD) where a rush current accompanied with the stepwise change of the target temperature of the TEC. First, the controller stops the TEC driver prior to the setting of the target temperature, and sets the present temperature of the LD. Subsequently, the controller gradually increases the reference temperature of the TEC in stepwise to the target temperature. Thus, the controller suppresses the rush current accompanied with the instantaneous increase of the reference temperature of the TEC.

Abstract: An optical transmitter is disclosed that provides a function to resume the APC operation automatically when the failure of the APC operation is due to the thermal runaway of the device in the APC loop. The controller included in the transmitter always monitors the bias current supplied to the LD, and the optical output from the LD. When the bias current exceeds a threshold, the controller decides whether the abnormal is due to the temporary thermal runaway or the fatal failure of the device within the APC loop, and begins to sense the ambient temperature of the LD for appropriate resuming after the thermal runaway is cleared.

Abstract: An optical receiver implemented with two electronic dispersion compensators (EDC) is disclosed. The optical receiver selects one of the EDC in an ordinary operation. Once there shaped signal compensated by the selected EDC is degraded due to irregular conditions of the optical transmission line, the optical transmitter and so on, the optical receiver reconfigures the tap coefficients of the unselected EDC and switches to the newly configured EDC after setting the tap coefficients for the new condition of the transmission line and the transmitter.

Abstract: The present invention provides an optical transmitter that enables to distinguish failure modes of the auto-power control (APC) of the laser diode (LD). The transmitter provides the APC circuit comprised of the driver for supplying the driving current, the LD, the PD for monitoring a portion of the output light from the LD, and the control unit for setting the driving current. The control unit monitors, at regular intervals, the bias current to the LD and the time differential of the bias current. The control unit only stops the APC circuit when both the bias current and the time differential of the bias current exceed respective references.

Abstract: A pluggable optical transceiver with a function not affecting the command status of the host system appeared in the internal bus, which is coupled with the command line within the transceiver, even when the transceiver is plugged in the host system. The optical transceiver provides a power supply circuit and a control unit. The power supply circuit, by receiving an external electric power, generates an internal electric power with a substantial time lag from a moment when the optical transceiver is plugged in the host system. The control unit communicates with the host system through the command line pulled up to the external electric power within the optical transceiver.