A polarization-maintaining optical fiber includes a core region and a cladding region formed around the core region. Forming the active region contact trench includes performing a first etch to form a first contact trench depth associated with a first region, and performing a second etch to form a second contact trench depth associated with a second region. The process shown is performed at lower temperatures than the prior art, which inhibits unwanted species migration and unwanted reactions with the silicon substrate or other structures. The seat belt webbing is cinched between the lock bar and the end flange when the lock bar is in the locked position.