Is it safe to get ipl done under the arm with breast implants?

Yes, it is safe!: Intense pulsed light treatments are broadband (full spectrum), and do not use lasers (single wavelength) or ionizing (ultraviolet or x-ray) wavelengths. They are for pigmented and vascular lesions (superficial ones) and sometimes hair reduction. These energies do not penetrate beyond a mm or two, so your implants will not be affected in any way. The same applies to laser hair removal-perfectly ok!

Yes : Should be safe to proceed with ipl and/or any other skin procedure after breast augmentation surgery.

Aug vs Reconstruct?: As long as you don't have a transaxillary approach/incision and as long as it has been several months since surgery to allow for resolution of axilla ray swelling and postoperative inflammation. My concern is you describe this as breast reconstruction which can remove axillary lymph nodes and more prone to swelling/infection if a lymph node dissection was performed. Ask your plastic surgeon.