Design For The Project Of High-Stabilization Temperature Control Module System And Experiment Argumentation

Communication technology leads the global development in everyfield. A piece of information took quite a long time and manpower to betransferred before. Now we can know what are happening in any corner of theworld at home just by pressing the mouse lightly, which profits from theflourishing development of network and communication technology. Due tothe optical communication technology developed in recent years, the rate,distance and reliability of communication transfer have entered a new step.With the development of optical fiber communication, optical amplifier showsmore and more important effect. EDFA(Er Doped Fiber Amplifier), applicableto C wave band, and full wave band online RAMAN amplifier, made thecapacity and distance of the information transferred in optical fiber developfarther. Although there are only about30 years since the semiconductor laserappeared the first time, the new material and technology about it developedvery quickly .From the homojunction, the heterojunction to the quantum welland the strained multi-quantum well ,the semiconductor has played more andmore important role in the information society as the core of thesemiconductor optoelectronics. And with its superior characteristic ,it haspenetrated into the area which the other lasers cannot set foot in .For the abovefacts ,it has drawn wide attention ,and at the same time ,a higher qualitysemiconductor laser is needed. Semiconductor laser diode, as a core device ofoptical fiber communication, has the character of high efficiency, small size,low weight, high reliability, direct modulation and high integrated ability withother semiconductor devices. However, semiconductor laser diode is a kind ofdevice with high power density and sky-high quantum efficiency. Even weakdrive current and temperature change will lead to its large change of outputlight power. It can not work continuously under room temperature even if withsmall output power. At the same time, semiconductor laser diode is verysensitive to the temperature. The fluctuation of surrounding temperature notonly leads to the fluctuation of supply current, but also makes thresholdcurrent, quantum efficiency, output wavelength and output light intensity ofthe laser diode change greatly. No matter which field semiconductor laserdiode is applied to, it is always expected to work long and steadily. Especiallyin the benthic optical fiber communication system, semiconductor laser diodeis required to work more than 25 years. However, actually used semiconductorlaser diode can not meet people′s demand. Except of factor of the laser diodeitself, many other factors result in the deterioration and unsteadiness of thedevice, such as the fluctuation of surrounding temperature, improper drivecurrent, frequent impulse and heat dissipation. Therefore, the stable andconstant control of semiconductor laser diode is rather important. Based on the practices in engineering, in this paper some keytechnological problems are deeply discussed in designing the whole structuresand hardware, modeling and designing controlling strategy for this system.First, considering the technological requirements of the system and based onthe study and absorption of relative theories and technologies for the keyproblems, the whole structure of this system is designed which is satisfied forthe requirements of high reliability ,uniform distribution, the model beingcontrolled of this system is designed based on the over-all heat transfer theory.In the process of making PID control realized ,calculating precision isimproved by designing software and, designing hardware improves measuringand controlling precision of the system. This strategy is of excellent accuracyand strong robustness. The adjusting results prove that the requirement oftechnology of the system is satisfied in essence. Next, considering thecomplexity of the heating process of the system, such as the characteristicstime change and delay, the heating system has to be further studied based onadaptive control of its model. The feasibility of the method is verified bysimulation. And the simulating results prove this method is of excellentprospect. In constant temperature control, the principles of negative feedbackcontrol is also applied. NTC(negative temperature coefficient thermistor) isused to sense the change of temperature. TEC(thermoelectric cooler) is used tocontrol the temperature. The temperature sensor and TEC are integratedtogether into some commercial laser diode modules. Therefore, it is necessarythat the parameter of constant temperature controller is designed to match withthe temperature sensor and TEC in laser diode modules. The feed back signalfrom the temperature sensor and setting temperature signal make subtraction,the calculated error-signal is sent to PID controller, and then to TEC drivecircuit to control the magnitude and direction of the current in TEC. TEC is adevice driven by current. When the direction of the current in TEC is different,TEC may work as heating or cooling. According to different number ofcouples of TEC, TEC has different cooling power and maximum current.Therefore, the circuit of current limitation in constant temperature control canavoid that output current is higher than maximum current of TEC. In this paper,...