S1 SUPPLEMENTARY INFORMATION A black beam borne by an incandescent field selftraps in a photopolymerizing medium Kailash Kasala and Kalaichelvi Saravanamuttu* Department of Chemistry and Chemical Biology, McMaster University 1280 Main St. West, Hamilton, Ontario L8S 4M1, CANADA *Author to whom correspondence should be addressed at kalai@mcmaster.ca