Study On Wideband Tunable Laser Array Based On Reconstruction-equivalent-Chirp Technique

With the rapid development of information society,Internet traffic and access devices are increasing day by day.People’s demand for the bandwidth and the speed of the communication network is getting higher and higher.As a key component of the optical communication system,the tunable laser plays an important role in promoting the development of communication network.Among many types of tunable lasers,the Distributed Feedback(DFB)laser has become the most widely used light source in the optical communication network due to its advantages of good single-mode stability,high output power and good direct modulation performance.However,DFB laser also faces some problems such as high manufacturing cost,inaccurate wavelength and narrow wavelength tuning range.In this paper,based on the Reconstruction-Equivalent-Chirp(REC)technique,two different structures of multi-wavelength wideband tunable laser array are designed and demonstrated.Meanwhile,we set up a semi-automatic test system to improve the efficiency of the laser chip test and data acquisition.The main contents and results of this paper are as follows:1.A semi-automatic test system is built.The system is mainly composed of a carrier,probes,a Thermo Electric Cooler(TEC),holders for three-dimensional(3D)adjusting,power supplies,optical spectrum analyzers,optical power meters,optical fibers and optical couplers.The whole test system is controlled by the self-written program.In our experiments,all the operations can be completed by the program except for the chip placement and moving the holders for adjusting,which improves the efficiency of laser chip test and data acquisition.2.A monolithic integrated buried heterojunction tunable laser array based on REC technique is designed and demonstrated.The device integrates four DFB lasers,an active combiner and a semiconductor optical amplifier(SOA)in a size of 1500×250 μm2.The threshold currents of all the lasers are all about 10 m A.The output power is about 10 m W when the temperature is fixed at 20 ℃ and the current of the laser diode is fixed at60 m A.In the temperature range of only 15.5 ℃,the device can obtain twelve 100-GHzspacing channels and can be tuned continuously within a range of 9.6 nm.In addition,of all the channels,the side-mode suppression ratios(SMSRs)are more than 50 d B,showing the excellent single-mode stability.Moreover,the statistics measurement shows that 80.5% of the lasers’ lasing wavelength deviates from the designed wavelength within±0.2 nm,proving the precise wavelength control is achieved.3.A monolithic integrated wideband tunable laser array based on REC technique is designed and demonstrated.The device integrates 16 DFB lasers,an active combiner and an SOA in a size of 3000×250 μm2.The output power is about 5 m W when the temperature is fixed at 20 ℃ and the current of the laser diode is fixed at 70 m A.In the temperature range of only 18 ℃,the device can realize forty-eight 100-GHz-spacing channels and can be tuned continuously for a range of 38.4 nm.Besides,the SMSRs of all the channels are above 39.8 d B,which shows good single-mode stability.Furthermore,the statistics measurement shows that 89.3% of the lasers’ lasing wavelength deviates from the designed wavelength within ±0.2 nm,which reflects the precise control of the wavelength.