A method for determining a maximum transmission capacity, TCAP.sub.MAX-OL, of an optical link, OL, within an optical network includes loading an optical transmission spectrum of the optical link, OL, being partially occupied by at least one data traffic carrying channel, CH, with amplified spontaneous emission, ASE, noise spectrally shaped such that the transmission performance of the optical transmission spectrum fully occupied with data traffic carrying channels, CHs, is matched. The method further includes determining the maximum transmission capacity, TCAP.sub.MAX-OL, of the optical link, OL, on the basis of measured link data transported through the optical link, OL, via the at least one data traffic carrying channel, CH.

A single-ended data transmission system transmits a signal having a signal voltage that is referenced to a power supply voltage and that swings above and below the power supply voltage. The power supply voltage is coupled to a power supply rail that also serves as a signal return path. The signal voltage is derived from two signal supply voltages generated by a pair of charge pumps that draw substantially same amount of current from a power supply.

An article may include an optical transceiver package, which may include a photonics component mounted in the optical transceiver package. The photonics component may generate heat in an operational state. The optical transceiver package may include a sealed thermal chamber that maintains the photonics component between a lower predetermined working temperature and a higher predetermined working temperature. The sealed thermal chamber may include a material that exhibits a first thermal conductivity below a lower predetermined threshold temperature and a second thermal conductivity higher than the first thermal conductivity above an upper predetermined threshold temperature. A method may include retaining the generated heat to raise the photonics component above a lower predetermined working temperature, and conducting the generated heat away from the optical transceiver package to lower the photonics component below an upper predetermined working temperature. A system may include the optical transceiver package mounted to a printed circuit board.

Improvements in extinguishing optical signals in silicon photonics may be achieved by supplying a test signal of a known characteristics to a Photonic Element (PE) to extinguish the test signal via a first phase shifter and intensity modulator on a first arm of the PE and a second phase shifter and intensity modulator on a second arm of the PE; sweeping through a plurality of voltages at the first intensity modulator to identify a first voltage that is associated with an extinction ratio at an output of the PE that satisfies an induced loss threshold and a second voltage that is associated with an induced loss in the test signal at the output of the PE that satisfies an extinction ratio threshold; and setting the PE to provide an operational voltage to the first intensity modulator based on the first voltage and the second voltage.

Embodiments are disclosed for generating a lookup table value for calibrating a lookup table circuit in an optical transmitter. The example method includes generating a calibration signal. The calibration signal encodes a plurality of bits in a number of amplitude levels. The example method further includes transmitting the calibration signal to a module under calibration and transmitting a symbol sequence of defined length to a reference module. The reference module compares the symbol sequence with a distorted signal received from the module under calibration to generate a set of condition count statistics. The example method further includes receiving the set of condition count statistics from the receiver in the reference module and calculating a lookup table value based on the set of condition count statistics. The example method further includes transmitting the lookup table value to a transmitter associated with the module under calibration.

A photonic circuit testing device, including a photonic test chip including, on the side of a first surface of the chip: micropillars, each intended to be placed in contact with a corresponding electric connection pad of the photonic circuit; and first optical input/output ports, each intended to be optically coupled to a second corresponding optical input/output port of the photonic circuit.

Photonically integrated normal incidence photodetectors (NIPDs) and associated in-plane waveguide structures optically coupled to the NIPDs can be configured to allow for both in-plane and normal-incidence detection. In photonic circuits with light-generation capabilities, such as integrated optical transceivers, the ability of the NIPDs to detect in-plane light is used, in accordance with some embodiments, to provide self-test functionality.

Photonically integrated normal incidence photodetectors (NIPDs) and associated in-plane waveguide structures optically coupled to the NIPDs can be configured to allow for both in-plane and normal-incidence detection. In photonic circuits with light-generation capabilities, such as integrated optical transceivers, the ability of the NIPDs to detect in-plane light is used, in accordance with some embodiments, to provide self-test functionality.

Examples described herein relate to calibration of an optical communications link. Data signals received over the optical communications link are measured to obtain an eye scan. A height of an upper eye region and a height of a lower eye region are compared in the eye scan. A common mode calibration value is adjusted based on any difference in the heights. A common mode adjustment circuit is then controlled based on the common mode calibration value. The common mode adjustment circuit is configured to remove a direct current bias within a receiver for the optical communications link.

An optical transceiver includes processing circuitry to calculate, when test signals are sent to a transmission line from a transmitter and a receiver receives the test signals having passed through a wavelength filter, a bandwidth of the received test signals, the transmitter generating, as the test signals, a collection of narrowband signals, the narrowband signals having a narrower bandwidth than a bandwidth of the wavelength filter and having different frequencies, and the wavelength filter included in an optical splitter inserted in the transmission line, and the collection of narrowband signals including a narrowband signal having a higher frequency than a highest frequency in the bandwidth of the wavelength filter and a narrowband signal having a lower frequency than a lowest frequency in the bandwidth of the wavelength filter, and to determine a modulation rate and a modulation level of the transmission signal depending on the calculated bandwidth.