Study On In-line Current-tuned Laser Based On Reconstruction Equivalent Technique

With the advent of information explosion and the era of big data,social requirements for information transmission are getting higher and higher.High-speed transmission rate,especially the more flexible and intelligent communication network,has become the development direction of the optical communication.High-bandwidth,stable operation and low-cost tunable lasers will play an increasingly important role in this process.In addition,tunable lasers are also used in other non-communication fields such as phased-array radar,gas monitoring,sensing and measurement.The market is expanding year by year.However,the state-of-art of tunable lasers is still dominated by foreign companies,which results in high price for tunable lasers(the price can reach several hundred dollars).Therefore,it is of great significance to develop low-cost tunable lasers.This paper starts with fiber-optical communication,then it clarifies the principle of tunable lasers and the important role tunable lasers play in today's communication and non-communication systems.Then through the introduction of reconstruction equivalent chirp(REC)technology,it shows that semiconductor distributed feedback(DFB)laser based on REC technique has the advantage of relatively simpler process and lower production cost,which makes the production of low-cost tunable lasers possible.Multi-section in-line tunable DFB laser integrated with semiconductor optical amplifier(SOA)tuned by injection current is investigated.When the temperature is controlled at 25? and the injection current is increased from 30 mA to 170 mA,each laser can be tuned about 4.3nm,4nm and 4.4nm.The side mode suppressing ratios(SMSRs)exceed 35dB.Twenty-three channels of 50 GHz channel spacing are obtained,the wavelength tuning range is from 1554.13nm to 1562.93nm.In the next-generation optical communication intelligent network,the system putsforward higher requirements on the wavelength switching speed of the tunable lasers.To some extent,the wavelength switching speed affects the flexibility of optical communication network.The wavelength-switching time of the in-line tunable semiconductor laser is studied and measured.The measurement system is based on the Mach-Zehnder interferometer(MZI)with two arms having almost the same length.The measurements are studied both in theory and experiments.All the results are presented and discussed,to help the optimization of testing and packaging such tunable lasers in future.