“…Some recent work in this respect can be found in papers such as [1,3,25,26], however, they are exclusively restricted to the simple medium case. Few theoretical analysis has been carried out for Maxwell's equations when metamaterials are involved except the work [7,8] for time-harmonic problems, and our initial effort in finite element error analysis for time-domain problems [17,20,19]. But in all our previous work, we only considered implicit schemes.…”