Development of Ultra-broadband Wavelength Tunable Semiconductor Lasers

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Wavelength tunable semiconductor laser is the heart of the next generation optical transport networks where wavelength routing and addressing serve as core functions. In widely deployed wavelength division multiplexed fiber-optic telecommunication systems as well as in advanced data transmission systems, tunable lasers are much wanted as the backup source for saving the cost and solving complicated issues involved in multiple wavelength laser inventory. Chip level optical interconnects for computer data exchange relies on tunable lasers to establish full connections among nodes or cores, as the cross-link topology can be greatly simplified with wavelength added as an extra dimension. Sophisticated LiDAR systems, especially in driverless cars, need tunable lasers to gain more accuracy and to secure their functioning in adverse weather conditions. In sensor applications for medical and security purposes, and in optical measurement systems, tunable lasers enable wavelength scanning hence the system performance can be greatly enhanced in many aspects. Conventional approaches to change the lasing wavelength are all based on tuning the material refractive index. A major problem with these approaches, however, lies in their narrow tuning ranges, for the fact that the material refractive index can hardly be tuned beyond 1%. An elegant technology to expand the tuning range is to exploit the Vernier effect. However, the tuning is quasi-continuous with an even more serious issue rooted from the non-monotonic dependence of the lasing wavelength on the tuning force, which makes the searching of a proper bias combination for a required lasing wavelength lengthy and tedious. The objective of the proposed research program is to develop ultra-broadband wavelength tunable semiconductor lasers with completely new tuning methodologies. The fundamental difference in the proposed approach is to perform tuning by changing the properties of the optical wave, rather than by changing the properties of the material. Examples of changing wave properties for the tuning purpose include rotating the field polarization status, or steering the beam angle, or altering the degenerate status of the wave distribution. By exploiting the material anisotropicity and structural asymmetry, we aim at forcing the wave to experience significant effective index changes that will lead to a wavelength tuning range beyond 100 nm in a continuous and monotonic fashion. The concept that this research program will establish, the structure that it will invent, the device that it will demonstrate, and the knowledge through which we will acquire, will not only prompt the development of tunable lasers, but will also benefit a number of Canadian companies in relevant areas, such as Enablence, Lumentum/Oclaro (Canada), Ciena (Canada), and Huawei (Canada). The program will also generate a stream of highly skilled and much needed graduate students for Canadian industry.