Monolithic integration in InGaAs-InGaAsP multiple-quantum-well structures using laser intermixing

• Published in: IEEE journal of quantum electronics Vol. 33; no. 1; pp. 45 - 55
• Main Authors: McKee, A., McLean, C.J., Lullo, G., Bryce, A.C., De La Rue, R.M., Marsh, J.H., Button, C.C.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.1997; Institute of Electrical and Electronics Engineers
• Subjects: Absorption; Applied sciences; Circuit properties; Design and performance testing of integrated-optical systems; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Integrated optics. Optical fibers and wave guides; Laser tuning; Lasers; Monolithic integrated circuits; Optical and optoelectronic circuits; Optical elements, devices, and systems; Optical materials; Optical modulation; Optical processors, correlators, and modulators; Optical waveguides; Optics; Photonic band gap; Physics; Quantum well devices; Quantum well lasers; Semiconductor lasers; laser diodes; Waveguide lasers; Integrated optics; Gallium arsenides; Ridge waveguide; Ternary compounds; Multiple quantum well; Experimental study; Indium arsenides; Fabrication; Gallium phosphides; Semiconductor lasers; Indium phosphides; Electroabsorption modulators; Quaternary compounds
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.554876

The bandgap of InGaAs-InGaAsP multiple-quantum-well (MQW) material can be accurately tuned by photoabsorption-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. Bandgap shifts larger than 100 meV are obtainable using laser power densities of around 5 W/spl middot/mm/sup -2/ and periods of illumination of a few minutes to tens of minutes. This process provides an effective way of altering the emission wavelengths of lasers fabricated from a single epitaxial wafer. Blue shifts of up to 160 nm in the lasing spectra of both broad-area and ridge waveguide lasers are reported. The bandgap-tuned lasers are assessed in terms of threshold current density, internal quantum efficiency, and internal losses. The ON/OFF ratios of bandgap-tuned electroabsorption modulators were tested over a range of wavelengths, with modulation depths of 20 dB obtained from material which has been bandgap-shifted by 120 nm, while samples shifted by 80 nm gave modulation depths as high as 27 dB. Single-mode waveguide losses are as low as 5 dB/spl middot/cm/sup -1/ at 1550 mm. 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 demonstrated.