Today we talk about silicon photonic external cavity tunable lasers. Generally, tunable lasers and silicon photonic integrated chips are packaged together in a BOX. The box is including flexible plate, ceramic submount, sapphire window and adaptor.
The previous and current internal optical path structures are the same, but the ceramic electrical signal substrate has been optimized.
The early ceramic submount were multi-step, and the current ceramic submounts were thinned.
On the tungsten-copper base, the silicon photonics integrated chip and the gain chip are optically coupled, and the gain is added to an external resonant cavity to form an external cavity laser.
The front-end waveguide of the gain chip and the side waveguide of silicon photonics are rotated by 19.5° to avoid interference of the resonant cavity caused by end-face reflection.
The front end of the gain chip is anti-reflection, and the back end is made of high-reflection film, which becomes one of the reflection surfaces of the external resonant cavity.
This chip only has the ability to radiate light, and does not include a resonant cavity. Some manufacturers call it Gain, some manufacturers call it SOA, and some manufacturers call it RSOA, which means the same thing.
The top view is as follows
A group of micro rings are used as vernier combinations to tune the wavelength. This idea is consistent with the principle of silicon-based hybrid tunable lasers from Marvell, Acacia, and Intel.
The difference is that here the modulator is integrated on the silicon photonics chip. After the laser resonance can be completed on the silicon photonics chip and the wavelength is selected, it is input to the modulator, and then the modulated signal is output to the adapter through the collimator lens, isolator, and converging lens.
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