Configurable intensity-modulation direct detection (IMDD) optical transceivers
Implementations are directed to configurable intensity-modulation direct-detection (IM-DD) optical transceivers that are configurable between single-polarization (SP) operation and dual-polarization (DP) operation.
1 . A intensity-modulation direct detection (IMDD) transmitter comprising:
a first modulator configured to modulate a first optical signal;
a second modulator configured to modulate a second optical signal; and
a polarization beam-splitter rotator (PBSR) configured to receive the first optical signal and the second optical signal, and to output an output signal that is based on the first optical signal and the second optical signal,
wherein the IMDD transmitter is configurable between transmitting single polarization (SP) signals and transmitting dual polarization (DP) signals,
wherein the IMDD transmitter is configured to transmit DP signals by:
applying a first marker signal having a first frequency to the first optical signal, and
applying a second marker signal having a second frequency to the second optical signal, wherein the first frequency is different from the second frequency, and
wherein the IMDD transmitter is configured to transmit SP signals by disabling the second marker signal.
2 . The IMDD transmitter of claim 1 , comprising a variable splitter connected at its input to a laser and connected at its outputs to the first modulator and the second modulator.
3 . The IMDD transmitter of claim 2 , wherein the variable splitter comprises a Mach-Zehnder interferometer that comprises at least one phase shifter.
4 . The IMDD transmitter of claim 2 , wherein the IMDD transmitter is configured to transmit SP signals by controlling the variable splitter to provide a majority of light from the laser to the first modulator, and
wherein the IMDD transmitter is configured to transmit DP signals by controlling the variable splitter to provide half of the light from the laser to the first modulator and half of the light from the laser to the second modulator.
5 . The IMDD transmitter of claim 1 , wherein the IMDD transmitter is configured to transmit SP signals by further disabling the first marker signal.
6 . The IMDD transmitter of claim 1 , comprising:
a first digital-to-analog converter (DAC) configured to provide a first electrical signal based on which the first optical signal is modulated; and
a second DAC configured to provide a second electrical signal based on which the second optical signal is modulated,
wherein the IMDD transmitter is configured to transmit SP signals by disabling the second DAC.
7 . The IMDD transmitter of claim 1 , comprising:
a first laser configured to output first light having a first wavelength, wherein the first modulator and the second modulator are configured to receive the first light;
a second laser configured to output second light having a second wavelength, wherein the second wavelength is different from the first wavelength;
a third modulator configured to receive the second light and modulate a third optical signal based on the second light; and
a fourth modulator configured to receive the second light and modulate a fourth optical signal based on the second light.
8 . The IMDD transmitter of claim 7 , comprising:
a first variable splitter connected between the first laser and the first and second modulators; and
a second variable splitter connected between the second laser and the third and fourth modulators.
9 . The IMDD transmitter of claim 1 , comprising a laser configured to provide light to the first modulator and the second modulator,
wherein the first modulator and the second modulator are configured to modulate the light from the laser.
10 . The IMDD transmitter of claim 9 , wherein the IMDD transmitter is configured to switch between transmitting SP signals and transmitting DP signals by adjusting a relative amount of the light from the laser that is provided to the first modulator or the second modulator.
11 . The IMDD transmitter of claim 9 , comprising:
a first waveguide connected between the laser and the first modulator; and
a second waveguide connected between the laser and the second modulator.