Abstract: An all-fiber optical depolarizer is provided in which polarized light is controllably injected into a polarization beam splitter at a 45° angle. The beam splitter is combined with a loop made of standard non-birefringent fiber through which one of the polarizations split by the beam splitter circulates. The loop has a length greater than the coherence length of the light source. The interaction of the beam splitter and the loop produces incoherent depolarized light at the output transmission port of the beam splitter.

Abstract: A polarization-combining fused-fiber optical coupler is made of polarization maintaining (PM) fibers spliced to non-birefringent single mode (SM) fibers which are fused and drawn near the splicing to form a coupler with an adiabatic tapered profile. The linearly polarized light injected into PM fibers travels through the coupler where the power of the two polarizations is combined and transmitted to one output fiber. The method for producing such coupler involves splicing a pair of PM fibers to a pair of SM fibers, then injecting linearly polarized light into each PM fiber and fusing and drawing SM fibers to form an adiabatic coupler with maximum power transmission at a desired wavelength going to only one output fiber.

Abstract: An all-fiber optical depolarizer is provided in which polarized light is controllably injected into a polarization beam splitter at a 45° angle. The beam splitter is combined with a loop made of standard non-birefringent fiber through which one of the polarizations split by the beam splitter circulates. The loop has a length greater than the coherence length of the light source. The interaction of the beam splitter and the loop produces incoherent depolarized light at the output transmission port of the beam splitter.

Abstract: A polarization-combining fused-fiber optical coupler is made of polarization maintaining (PM) fibers spliced to non-birefringent single mode (SM) fibers which are fused and drawn near the splicing to form a coupler with an adiabatic tapered profile. The linearly polarized light injected into PM fibers travels through the coupler where the power of the two polarizations is combined and transmitted to one output fiber. The method for producing such coupler involves splicing a pair of PM fibers to a pair of SM fibers, then injecting linearly polarized light into each PM fiber and fusing and drawing SM fibers to form an adiabatic coupler with maximum power transmission at a desired wavelength going to only one output fiber.

Abstract: An active quench circuit for an avalanche current device applies a bias voltage to reverse bias an avalanche current device above its avalanche breakdown voltage; a current amplifier circuit having a turn-off speed slower than the avalanche speed of the avalanche device and responsive to the avalanche current of the avalanche device generates an overshoot current continuing after the end of the avalanche current; and a feedback circuit responsive to the overshoot current generates a quenching voltage for reducing the bias voltage below the avalanche breakdown voltage to quench the avalanche current of the avalanche device.