Photonic transceiver architecture with loopback functionality
Embodiments describe transceiver architectures to enable ‘loopback’ operation, thereby allowing or on-chip or intra module characterization of the transceiver. This includes but is not limited to tests such as bit error rate (BER) characterization, received power characterization and calibration of filters (MUX, DMUX etc.) present in the transceiver. Embodiments may also describe architectures for superimposing low-speed data on to the signal coming out of a transmitter, which in turn enables low frequency communication between network elements in the external link.
1. A transmission component, comprising:
a plurality of lasers each configured to produce single-wavelength light, the light from different lasers being at different wavelengths;
a multiplexer configured to combine the single-wavelength light from the plurality of lasers into a multi-wavelength light signal;
an output port configured to output the multi-wavelength light signal;
a switch operable to selectively direct the multi-wavelength light signal, responsive to a control signal, to the output port in an operation mode or to a loopback path in a loopback mode, the switch further being continuously tunable and selectively operable to pulse the multi-wavelength light signal according to received data to impose the received data on the multi-wavelength light signal to form a pulsed multi-wavelength light signal by sending a portion of the multi-wavelength light signal alternately to the output channel and the loopback path.
2. The transmission component of claim 1 , further comprising an attenuator configured to attenuate the multi-wavelength light signal directed into the loopback path.
3. The transmission component of claim 2 , wherein the attenuator is an absorber.
4. The transmission component of claim 2 , wherein the attenuator is a biased semiconductor optical amplifier.
5. The transmission component of claim 1 , further comprising a detector configured to detect a portion of the multi-wavelength light signal directed into the output channel.
6. The transmission component of claim 5 , further comprising a controller configured to control the switch synchronously with the received data in response to a signal from the detector.
7. The transmission component of claim 6 , wherein the controller is configured to control the switch to:
maximize the signal from the detector when the switch directs the multi-wavelength light signal into the output channel, and
minimize the signal from the detector when the switch directs the multi-wavelength light signal into the loopback path.
8. The transmission component of claim 1 , wherein the switch includes one of a semiconductor optical amplifier, a thermo-optic switch or a p-i-n diode switch.
9. The transmission component of claim 1 , wherein the switch includes an asymmetric Mach-Zehnder interferometer.
10. The transmission component of claim 1 , wherein the switch is further configured to impose the received data on the multi-wavelength light signal via frequency-shift keying.
11. The transmission component of claim 1 , wherein the different wavelengths are all within one of the L, C, or S bands.
12. A method, comprising:
producing, by each of a plurality of lasers, single-wavelength light, the light from different lasers being at different wavelengths;
combining, using a multiplexer of a transmitter of an optical transceiver, the single-wavelength light from the plurality of lasers into a multi-wavelength light signal;
receiving a control signal;
in response to the control signal, operating a switch at an output of the multiplexer to selectively switch between a pulsed operational mode and a loopback mode;
in the loopback mode, operating the switch to direct the multi-wavelength light signal to a loopback path from the multiplexer to a receiver of the optical transceiver rather than to an output port of the optical transceiver; and
in the pulsed operational mode, operating the switch to pulse the multi-wavelength light signal according to received data to impose the received data on the multi-wavelength light signal to form a pulsed multi-wavelength light signal at the output port by sending a portion of the multi-wavelength light signal alternately to the output port and the loopback path, outputting the pulsed multi-wavelength light signal at the output port, and dropping the portions of the multi-wavelength light signal directed to the loopback path.
13. The method of claim 12 , further comprising attenuating the multi-wavelength light signal directed into the loopback path.
14. The method of claim 12 , further comprising detecting a portion of the multi-wavelength light signal directed into the output channel.
15. The method of claim 14 , further comprising controlling the switching synchronously with the received data in response to the detected portion of the of the multi-wavelength light signal.
16. The method of claim 12 , wherein the received data is imposed on the multi-wavelength light signal via frequency-shift keying.
17. A transmission component, comprising:
a plurality of lasers configured to produce single-wavelength light at different wavelengths;
a multiplexer configured to combine the single-wavelength light from the plurality of lasers into a multi-wavelength light signal;
an asymmetric Mach-Zehnder interferometer configured to selectively switch the multi-wavelength light signal between an output channel and a loopback path;
a detector configured to detect a portion of the multi-wavelength light signal directed into the output channel;
a controller configured to control the asymmetric Mach-Zehnder interferometer in response to a signal from the detector, the controller further configured to control the asymmetric Mach-Zehnder interferometer to maximize the signal from the detector when the asymmetric Mach-Zehnder interferometer directs the multi-wavelength light signal into the output channel, and minimize the signal from the detector when the asymmetric Mach-Zehnder interferometer directs the multi-wavelength light signal into the loopback path, the controller and the asymmetric Mach-Zehnder interferometer forming a pulsed multi-wavelength light signal; and
an output port configured to output the pulsed multi-wavelength light signal.