Research On MEMS-Based Tunable External-Cavity Semiconductor Laser

With the development of technology of tunable laser,it is primarily applied in opticalnetworks,sensing,as well as in precise measurements.Wavelength tunable lasers are verydesirable for increasing the capacity,functionality,specialty,and flexibility of the nextgeneration coherent communication systems.Because of the significant advantages of theexternal cavity lasers,such as wide tuning ranges,high output power,narrow linewidth andaccurate wavelength control,it has received considerable attention in recent years.The rapiddevelopment of MEMS(Micro-Electro-Mechanical Systems) technology makes it possibleto integrate tunable components into a chip level,so that both the size and cost of lasers canbe greatly reduced.MEMS-based tunable external cavity laser can be one type of the idealcommercial tunable laser.First,this paper introduces the current development of tunable lasers,compares theperformance of different kinds of tunable laser. Then,the theories of the tunableexternal-cavity semiconductor laser are described,the output characteristics and theirsinfluencing factors are analyzed.After investigating different structures of the tunableexternal-cavity semiconductor laser,the common components are summarized.Finally,anovel structure of tunable external-cavity semiconductor laser is designed.A MEMS-basedtunable filter is used as wavelength selection component, a silicon etalon with50GHzITU-T grid is implemented to make the output wavelength ITU-T compatible. We useLC(Liquid Crystal) cell as phase compensation element. The experimental results showthat the laser can provide12dBm output power with50dB side mode suppression ratio, a40nm tuning range and200kHz linewidth are also achieved. This paper has somereference value on developing commercial tunable external cavity laser.