| With the development of opticelectronic teachnology, microectronic teachnology, computer science and teachnology, automatic teachnology and so on, we have come into a world which is full of information and intelligence. Semiconductor laser as light source that produces an excellent optical signal is an important teachnology that many countries pay great attention to. Ever since the birth of the first semiconductor laser in 1980s, its related technology development is very fast. And gradually formed a series of scientific branches, such as semiconductor optoelectronics, integrated optics, guided wave optics and so on. Semiconductor laser has obtain applications in optical fiber communication, optical senser, optical storage, and optical information process and some other fields.Upgrading telecommunication networks to increase their capacity and intelligence are becoming increasingly important due to the rapid increase in network traffic. Wavelength division multiplexing (WDM) provides can be easily added into the existed network to increase their capacity, Optical add-drop multiplexer (OADM) and optical cross-connect device (OXC) can be a good method to increase their intelligence, a laser source with a wide tuning range is a key device to form those system. Moreover, for many applications in interferometer and spectroscopy, a laser source which can be tuned over a wide spectral range without mode hopping is needed. In wavelength scanned interferometer, for example, mode-hopping is detrimental to spatial resolution or the position accuracy of distance measurements. And so a novel semiconductor laser which can achieve mode-hop-free tuning is proposed in this article.At present there are many wavelength tunable laser structures, some can not achieve mode-hop-free tuning due to its structure defect, some due to its ignorance of mode-hop-free tuning. To achieve mode-hop-free wavelength tuning, the tuning rate of the laser cavity and the tuning rate of the wavelength-selective element must be synchronous. For monolithically integrated lasers, two synchronous tuning electrodes are usually required for mode-hop-free tuning. To avoid using multi-electrode simultaneous tuning architecture which needs complicated tuning algorithms and so limits the tuning speed, several single-electrode tuning structures have been proposed by using a tunable twin guide (TTG) layer structure. However, the laser requires very complex multiple regrowth and etching fabrication process. a novel mode-hop free tuneable diode laser is proposed. The laser consists of an active waveguide to provide optical gain,an Etched Diffraction Grating (EDG),which serves as dispersion element to select mode, a tuning region which is placed on the diffraction region of the EDG.The shape of the tuner is properly designed so that the laser can achieve mode-hop-free tuning with single electrodes.For a mode-hop-free tunable laser, besides no mode hops, Side-mode suppression ratio and tuning range are two important performances of the laser, which need to carefully design the detailed structure parameters. In this article, we design the EDG using 1-stigma method. Selecting a suitable length of the active waveguide which can provide surfficient gain, the shape of tuning section is optimized, so that the laser can achive a wide tuning range under certain injecting current. At the same time this article also studied the integration of active and passive waveguide and gives the corresponding waveguide parameters and some simulation results so as to prove good coupling efficiency and single-mode characteristics in the coupling process.Finally, the mask and fabrication process of the proposed mode-hop-free tunable laser based on EDG structure is studied, and then we discussed the manufacturing process of integrated optoelectronic device, including clean wafer, lithography, metal sputtering, lift off and dry etching, and we get some good experiment results, which are helpful to fabricated our proposed mode-hop-free laser successfully. |
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