Hallo Abhishek,

if you need to drive unipolar stepper motor and want opto isolation, you could try the following circuit:



2N3906 translates negative logic of 8052 micro and turns on opto coupler. I prefer using 6N136, because it's some faster than 4N35 or similar. Output side of 6N136 is fed to 74HC14 containing Schmitt-trigger inputs, which are needed, because rise and fall times at input of this gate are not fast enough for standard inputs (transition time is >500nsec).

As you wrote, that only 1A has to be sinked by IRFZ44, I think that a gate source voltage of 5V should be enough to turn-on the MOSFET adequately. So, a 74HCMOS gate should be suited to drive the IRFZ44.
You see a resistor of 250 Ohm at gate of IRFZ44. This resistor together with two protection diodes internally of 74HC14, connected from output pin to supply rails, is part of a protection circuit which will prevent latch-up of 74HC14 output. But 250 Ohm resistor has another task: In combination with gate source capacitance a low pass filter is formed, which slows down a bit the turn-on and turn-off time of IRFZ44. Especially turn-off time in combination with inductive load can be critical: If an inductive load is turned-off very fast, an enormous voltage pulse can be created by induction. Problems can then arise, if clamping measures like free wheeling diodes, etc. turn-on slowlier than overvoltage pulse is created. So, voltage rise due to induction should be slowlier than turn-on time of clamp circuitry.
This 250 Ohm resistor can be increased up to 1kOhm, or so, but shouldn't be decreased. All depends, of course, by which frequency you want to control the stepper motor...

In the schematic no additional clamping device is shown. It's assumed, that the body diode internally of IRFZ44 (from source to drain) with it's specified avalanche performance is capable to handle the inductive voltage pulse. But as long as I don't know, what kind of stepper motor is used, I cannot guarantee, that this clamping measure will be enough!
Many manufacturers of stepper motors suggest certain snubber or clamping circuits. These recommendations should be followed. One way to additionally protect the IRFZ44 is to add a transzorb from drain to ground. Turn-on threshold should be well below maximum drain source voltage of IRFZ44, of course. On the other hand, if threshold voltage is choosen too low, it needs more time to make break down the magnetic field.

Good luck,
Kai