The present invention describes the use of multi-wavelength laser array (MLA) to construct a low-cost tunable semiconductor laser. The MLA utilized a proprietary technique named as reconstruction-equivalent chirp (REC), which was firstly proposed by the inventor of this project. The high performance of MLAs can be achieved with the use of REC technique instead of electron beam lithography (EBL), which is an expensive fabrication method. The chip fabrication process can thus be simplified and the production cost can be reduced. This technique also has a special advantage on controlling the wavelength spacing of MLAs, which can yield more accurate wavelength spacing than other existing fabrication techniques. A special in-line arrangement of the array is also employed to simplify the hardware packaging for further decreasing the device assembling cost. Utilizing the technology and applying the designed packaging in producing a tunable laser can keep the cost below US $100. The developed device has the potential to be adopted in network systems such as NG-PON2.
The tunable lasers that are currently available in the market include, external cavity laser, Distributed Bragg Reflector (DBR) laser and Distributed Feedback (DFB) laser array. There are some disadvantages associated with the use of these technologies in tunable lasers, e.g. the assembling cost of external cavity laser is high; the circuit control of DBR laser is complicated; the fabrication of DFB laser array usually involves the use of EBL technique, which is also expensive for production. The use of REC technique in the developed technology can precisely control the laser wavelength of the MLAs as well as largely reduce the cost of production.
The newly developed tunable laser can be widely applied in WDM-PON system. The market is expected to be huge, as each user unit should be installed with one tunable laser. The technology has the potential to be used in the future 5G communication facilities as it can support large data flow. The tuning speed is capable of reaching nano-second level. This feature allows the use of the device in data center of optical switching network.