Accession Number : ADP008148

Title :   Photon-Echoes in a Pumped Er-Doped Fiber,

Corporate Author : BELL COMMUNICATIONS RESEARCH INC RED BANK NJ

Personal Author(s) : Da Silva, V. L. ; Silberberg, Y.

Report Date : APR 1992

Pagination or Media Count : 2

Abstract : Recently we reported the first photon echo experiments in Er-doped fibers, and described their application to ultrafast time domain signal processing. Our previous results were obtained with absorbing Er-doped fibers at 4 deg K and our signals at 1.53 micron were attenuated by the fiber. In this paper we report photon echo experiments with Er-doped amplifiers. We expect the photon echo process in amplifiers to yield strong echoes, perhaps stronger then the input signal. This could be important for signal processing applications. To our knowledge this is the first demonstration of photon echo in any inverted system. Photon echo is a coherent optical effect which is observable on time scales shorter then the homogeneous dephasing time of the system. The dephasing time of the 1.53 micron 4I15/2-4I13/2 erbium transition in silica at 4.2 deg C is about 1 nsec. At this temperature the transition is inhomogeneously broadened, with a width which is about 1000 times that of the homogeneous width. The main difficulty in this experiment is to pump the entire inhomogeneous line. Most pump sources used to pump room-temperature Er-doped fibers are much narrower then the 10 nm wide inhomogeneous line, and therefore they will pump only a small fraction of the population in a cooled fiber. In our experiment we have used a modelocked Ti:Sapphire laser at 810 nm. The 1.2 psec pulses from the laser are about 0.5 nm wide, however, after propagating through a few meters of optical fiber they are broadened through self-phase-modulation to more than 15 nm. A few hundreds milliwatts could be coupled to the cooled fiber.

Descriptors :   *FIBER OPTICS, *SYMPOSIA, AMPLIFIERS, ECHOES, ERBIUM, LASERS, PHASE MODULATION, PHOTONS, PULSES, PUMPS, SIGNAL PROCESSING, TRANSITIONS, DOPING, OPTICAL PUMPING.

Subject Categories : Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE