Integrated coherent optical transceiver, light engine

An integrated coherent transceiver comprising:

• a substrate member;
• a tunable laser device comprising a laser diode chip having a gain region with a p-side electrode flipped down and mounted on the substrate member, the gain region being coupled with a wavelength tuning section formed in the substrate member to tune wavelengths of a laser light outputted from the gain region to a waveguide in the substrate member;
• a first power splitter coupled to the waveguide to split the laser light to a first light and a second light;
• a coherent receiver block comprising at least two 90° hybrid receivers coupled respectively to two outputs of a polarization beam splitter rotator in the substrate member to receive a coherent input signal from a coherent optical network and to two outputs of a second power splitter to receive two local-oscillator signals split from the first light for assisting detections of a transverse electric (TE) mode signal and a transverse magnetic (TM) mode signal in the coherent input signal;
• and
• a coherent transmitter block comprising at least a pair of in-phase/quadrature-phase modulators in the substrate member to respectively modulate two parts split from the second light to two I/Q-modulated signals in TE-mode, a polarization beam rotator combiner in the substrate member to rotate one of the two I/Q modulated signals to a TM-mode signal and combine with the other one of two I/Q modulated signals in TE-mode to generate a coherent output signal transmitted through a polarization-independent semiconductor optical amplifier to the coherent optical network.