Reconfigurable Optical Networks will be developed based on reconfigurable optical devices implementation into networks with new tunable and switchable functionalities by means of optical control. Between several optics devices with more specific functionalities we are working to perform the photonic devices with the specific functions like wavelength selector, multiplexer/de-multiplexer as well as even the spectrometer.
So having even each with other seems to have the closed operation, but each of them is different in order to meet their specific working requirements. Because there are a greater diversity of works performed for development of each of application nominated as above could be selected only few of works and results for a short information as below: Due of very short space more results about 2D Photonic Crystals performed into photonic devices could be displayed by the next Newsletter Wavelength selector. Because the integrated hardware system development is essentially has continued the works for finalisation of set-up of wavelength selector ( schematic drawing. of proposal) as well as for proof of concept validation. To be realized the set-up of workable wavelength selector had to be performed the design/development and manufacturing works of specific subsystems/electronic modules with further integration into optical system. The light sources selected to be used for our application are two types of laser diodes for two different wavelength as 635 nm and respectively 515 nm. For optimal operation of selected light sources had to develop the Driver for Laser diode with analog modulation. The driver system uses the internal monitor photodiode on most low power diode lasers for feedback when operating in the Constant Power Mode. The Figure 1 shows the block diagram of the laser diode driver of picture with the corresponding electronic module.
Figure1: a) The simplified block diagram of Driver b) Driver module front-end and back-end
The laser power is regulated through an integrating feedback loop. The setpoint of the feedback is determined by the PWR Limit control trimpot and the Output Adjust knob. An internal transimpedance amplifier converts the laser feedback current to a voltage that is used as the error signal for the feedback loop. Since all analog signal levels are based on a 2.5 V internal reference, will use this to derive the feedback gain setting resistor value. The Power supply modules. for laser diodes for 515nm and 635nm which need different voltage of supply as 5 VDC and 9 VDC developed and performed the corresponding power supply modules.
The photodetector module. Further works performed for implementation after that several testing/experiments revealed our requirements for best efficiency and higher sensitivity to integrate in our photodetector module, a photodiode with a wider area of light collection.
Figure 2: a)The photodiode connection circuit b) Diagram of variation wavelength/responsivity
