I found this amazingly inexpensive, 25W, 808nm laser on ebay tonight. I was quite tempted to buy it as it appears to be a very complete unit, including power supply, cooling, power meter, and output fiber. Unfortunately, it appears that ice doesn't absorb much at the 808nm wavelength, so I guess I'll pass on this one. I finally found an outstanding data source for optical properties of water and ice. Based on this information, I'd say I need a wavelength of at least 980nm.