Embodiments of the disclosure provide control systems and methods for controlling a pulsed laser diode and a sensing device including a pulsed laser diode. An exemplary control system includes a distance detector configured to generate a distance signal indicating a distance between the pulsed laser diode and an object reflecting pulsed laser beams emitted by the pulsed laser diode. The control system may also include a controller configured to dynamically control power supplied to the pulse laser diode based on the distance signal.

A method for performing ONU Management and Control Interface (OMCI) synchronization includes receiving an OMCI message containing a OLT-G entity identifying OLT's vendor identification (ID) and version. The method also includes determining if an OLT vendor identification (ID) matches with a current vendor ID and if an Optical Line Terminal (OLT) version is compatible with current OMCI handlers. When the OLT vendor ID fails to match with the current vendor ID, automatically performing a OMCI handler switching process. The OMCI handler switching process includes setting a current OLT vendor as a new OLT vendor ID, deleting a OMCI configuration previously stored in the flash memory after setting the new OLT vendor ID, and rebooting the ONT to allow the ONT to initialize a OMCI configuration using a new OMCI profile.

An amplitude modulation circuit includes: first, second, and third input terminals; first and second output terminals; a current source; first and second transistors including a base electrically connected to the first and second input terminals, a collector electrically connected to the first and second output terminals, and an emitter electrically connected to a grounding terminal via the current source; first and second resistive elements electrically connected between the first and second output terminals and a power line; and a first MOS transistor including a drain connected to the first output terminal, a source connected to the second output terminal, and a gate connected to the third input terminal. The MOS transistor is configured to operate in a non-saturated region, and a resistance between the source and the drain of the MOS transistor is larger than resistances of the first and second resistive elements.

A shutdown circuit may include a filter, for receiving a laser trigger signal for a laser emitter, that is configured to output a filtered signal. The shutdown circuit may include a logic gate configured to receive the filtered signal and at least one of a first signal based on a signal from a photodiode or a second signal based on a signal from a conductive path. The shutdown circuit may include a flip-flop configured to receive an output of the logic gate and to output an enablement signal that is based on the output of the logic gate, and a driver circuit for a switch configured to control current flow to the laser emitter. The driver circuit may be configured to receive the enablement signal and the laser trigger signal and to output the laser trigger signal based on whether the enablement signal is a first or a second voltage.

A shutdown circuit may include a filter, for receiving a laser trigger signal for a laser emitter, that is configured to output a filtered signal. The shutdown circuit may include a logic gate configured to receive the filtered signal and at least one of a first signal based on a signal from a photodiode or a second signal based on a signal from a conductive path. The shutdown circuit may include a flip-flop configured to receive an output of the logic gate and to output an enablement signal that is based on the output of the logic gate, and a driver circuit for a switch configured to control current flow to the laser emitter. The driver circuit may be configured to receive the enablement signal and the laser trigger signal and to output the laser trigger signal based on whether the enablement signal is a first or a second voltage.

An optical transmitter based on optical time division multiplexing is disclosed, which may solve the issues of complex structure and operation of a multilevel-OTDM-based optical transmitter while using a multilevel signal modulation format and OTDM technology that may increase the transmission rate of an optical transmitter with limited bandwidth.

An optical transmitter based on optical time division multiplexing is disclosed, which may solve the issues of complex structure and operation of a multilevel-OTDM-based optical transmitter while using a multilevel signal modulation format and OTDM technology that may increase the transmission rate of an optical transmitter with limited bandwidth.

An optical transmitter, having an encoder and modulator, transmits a data signal. The encoder maps information bits of the data signal to a symbol in eight-dimensional (8D) constellation space spanned by vectors IXT1, QXT1, IYT1, QYT1, IXT2, QXT2, IYT2, QYT2, wherein I and Q are in-phase and quadrature components of an optical carrier, X and Y are orthogonal polarizations of the optical carrier, and T1 and T2 are two consecutive transmission time slots, by selecting the symbol from a set of constellation points in the 8D space. The modulator uses the symbol in the two consecutive transmission time slots to modulate two carrier waves, and to transmit the two carrier waves over the orthogonal polarizations of the optical carrier. The set of constellation points do not include any constellation point with parallel Stokes vectors in the two consecutive transmission time slots but comprise constellation points with orthogonal Stokes vectors.

An optical transmitter, having an encoder and modulator, transmits a data signal. The encoder maps information bits of the data signal to a symbol in eight-dimensional (8D) constellation space spanned by vectors IXT1, QXT1, IYT1, QYT1, IXT2, QXT2, IYT2, QYT2, wherein I and Q are in-phase and quadrature components of an optical carrier, X and Y are orthogonal polarizations of the optical carrier, and T1 and T2 are two consecutive transmission time slots, by selecting the symbol from a set of constellation points in the 8D space. The modulator uses the symbol in the two consecutive transmission time slots to modulate two carrier waves, and to transmit the two carrier waves over the orthogonal polarizations of the optical carrier. The set of constellation points do not include any constellation point with parallel Stokes vectors in the two consecutive transmission time slots but comprise constellation points with orthogonal Stokes vectors.

A pluggable optical module according to the present invention includes a pluggable electric connector configured so as to be insertable into and removable from an optical transmission apparatus, and capable of transmitting/receiving a data signal to/from the optical transmission apparatus, a drive unit configured to output first/second driving signals by amplifying the data signal, an optical signal output unit configured to output a first/second optical signal modulated according to the first/second drive signal, a light-intensity monitoring unit configured to monitor intensities of the first/second optical signals, a control unit configured to control a gain of the drive unit so as to adjust a difference between the intensities of the first/second optical signals based on a result of the monitoring by the light-intensity monitoring unit, and a pluggable optical receptor configured so that an optical fiber can be inserted thereinto and removed therefrom, and configured to output the first/second optical signals.