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Opt Lett. 2013 Aug 15;38(16):3050-3.
Zhang C, Liang S, Zhu H, Wang W.
Key Laboratory of Semiconductor Material Sciences, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China.
Abstract
A widely tunable dual-mode distributed feedback (DFB) laser fabricated by selective area growth (SAG) technology integrated with Ti heaters was demonstrated. In the device, an original mode spacing of 4 nm was obtained by the simple SAG technology. Ti thin-film heaters were integrated with a novel procedure, which simplifies the fabrication of such heaters greatly. A large electrical resistance of the heaters is obtained at the same time, resulting in a high wavelength tuning efficiency. An accurate mode spacing as small as 0.34 nm and as large as 8.06 nm is achieved, which corresponds to a wide beat frequency range from 42.2 GHz to 1 THz. The simple fabrication process indicates that it is promising for reducing the cost of dual-mode DFB laser in fabricating self-pulsation lasers and THz generators.
Additional Information
Compared with E-beam exposure, schemes which utilize a uniform grating obtained by holographic exposures have also been used and have the advantage of higher reliability and lower fabrication cost. Selective area growth (SAG) technique by metal organic vapor phase epitaxy (MOVPE) is a more attractive method to generate different lasing wavelength with uniform grating. The thickness of material can be controlled with very high precision during MOVPE growth to generate accurate lasing wavelength for each DFB laser. The effective index of the SAG materials can be modulated by adjusting the geometry of mask patterns including mask width and separation between mask stripes. Thus, SAG is very fitful for mass production of low cost dual-mode DFB lasers with a simple procedure. For practical use in self-pulsation or THz devices, a widely tunable range of mode spacing is needed to match a series of predefined spacings. Ti thin-film heaters are also integrated for each DFB laser with a novel procedure, which simplifies the fabrication of such heaters greatly. The measured results of wide mode spacing presented above indicate that the dual-mode DFB laser fabricated by SAG method integrated with Ti-heaters can be used for the fabrication of high performance multi-section DFB self-pulsation lasers and THz emitters.
