Yep.
It's MDC, Miniature Detonating Cord, which is a thinner version of the 'cord' used for detonating explosives, burning at between 15,000 and 18, 000 metres per second. When 'blanked', that is, kept as a circuit or with 'stops' set into it, it will explode instantly along it's length. In this form, normal Det Cord can be used as a cutting charge, for instance to drop a tree. In the MDc's set into the canopy, the instantanteous explosion shatters the canopy, allowing the ejector seat to pass through.
This is used on those aircraft types where the canopy can not be jettisoned safely as part of the ejection sequence, and is initiated by the first stage of pulling the firing handle on the seat. It tends to be employed more on military aircraft employed in the low level role, or on carrier ops, where the slight delay of a jettisoning canopy would be crucial in the event of ejection.