A 2-WAVE-GUIDE TAPERED VELOCITY COUPLER FOR A VARIABLE DIVIDER OF OPTICAL POWER

A two-waveguide tapered velocity coupler is presented for a variable d ivider of optical beams. The coupler consists of one tapered slab wave guide in dimension and the other slab waveguide with a constant film t hickness. It is assumed that the device is fabricated on a LiNbO3 subs trate, with a push/pull external electric field parallel with the opti c axis applied only in the film regions of the coupler. Various numeri cal simulations through the finite difference beam propagation analysi s show that a wide range of dividing ratios from - 15 dB to 15 dB or m ore can be achieved with considerably small values of driving-voltage electrode-length product and that the dividing characteristics are sta ble over a wide range of frequencies.