Abstract: A surge protection apparatus (20) has a first quadrature coupler (22) with a first input (24) coupled to an electrical ground (26), and a second input (28) connected to an input signal. A second quadrature coupler (34) having a third input (32) is coupled to a first output (30) of the first quadrature coupler (22). A fourth input (38) is coupled to a second output (36) of the first quadrature coupler (22). A third output (40) is coupled to a signal port and a fourth output (42) is coupled to the electrical ground.

Abstract: A laser diode coupling and bias circuit (50) includes a laser diode (84) in a hermetically sealed housing (80) having a pair of inputs (76, 78). The laser diode (84) is attached to a printed circuit board (52). The printed circuit board (52) has a number of connection points and a ground plane. One of the pair of inputs (76, 78) of the laser diode (84) is coupled to one of the connection points (86) that is electrically connected to the ground plane of the printed circuit board (52). A second (76) of the pair of inputs (76, 78) of the laser diode (84) is connected to a second (76) of the connection points. An input transmission line (54) is attached to the printed circuit board (52) at a modulation input connection (56) and at the second (76) of the connection points. The input transmission line (54) has a blocking capacitor (72). A two pole equalization filter (74) is coupled between the input transmission line (54) and the ground plane.