Fabrication of quantum well photonic integrated circuits using laser processing

The bandgap of InGaAsInGaAsP multiple-quantum well (MQW) material can be accurately tuned by photo-absorption induced disordering (PAID), using a Nd:YAG laser, to allow lasers, modulators and passive waveguides to be fabricated from a standard MQW structure. The process relies on optical absorption in the active region of the MQW to produce sufficient heat to cause interdiffusion between the wells and barriers. Blue shifts of up to 160 nm in the lasing spectra of both broad area and ridge waveguide lasers are reported. Bandgap tuned electro-absorption modulators were fabricated and modulation depths as high as 27 dB were obtained. Single mode waveguide losses are as low as 5 dB cm−1 at 1550 nm. Selective area disordering has been used in the fabrication of extended cavity lasers. The retention of good electrical and optical properties in intermixed material demonstrates that PAID is a promising technique for the integration of devices to produce photonic integrated circuits. A quantum well intermixing technique using a pulsed laser is also reported.