Question:
I have a project to design a basic smoke detector using ionisation sensors or optical sensors (not LDR's). I have no idea on where to start looking for the supply of the sensors or how the driver circuit should be designed.

Answer: -You could measure the turbidity of the air by measuring the amount of light passing between to sides of a device... I think I was something like that for measuring water turbidity, and something similar would work for you I think... smoke would block a lot of light. Maybe a LED on one side, and a photoresistor on the other... then use and ADC to get a clean logical signal.

-Motorola's Sensor Division makes a number of smoke detectors based on two different prinicples. I suggest you look at their web site and at the data sheets and appliction notes for their parts to get a start.