Spatial-spectral holographic correlator at 1536 nm using 30-symbol quadriphase- and binary-phase-shift keyed codes.

Optical 30-symbol quadriphase-shift keyed (QPSK) and binary-phase-shift keyed (BPSK) codes were processed in a spatial-spectral holographic correlator with the Er(3+): Y(2)SiO(5) spectral hole-burning material operating at 1536 nm in the important 1550-nm communications band. The results demonstrate the ability of spatial-spectral holographic correlators to process QPSK codes and BPSK codes with the same apparatus. The high-fidelity correlations produced by this optical coherent transient device exhibit the low sidelobe characteristics expected for the codes used.

Demonstration of real-time address header decoding for optical data routing at 1536nm.

We have demonstrated real-time decoding of 20-bit biphase-coded address header pulses, using stimulated photon echoes in a phase-matched crossed-beam configuration. This decoding is one of the functions required for coherent transient optical data routing, packet switching, and processing. The active medium used was single-crystal Y(2)SiO(5) doped with Er(3+), which provides an operating wavelength of 1536 nm.

Measurement of photon echoes in ErY(2)SiO(5) at 1.5 microm with a diode laser and an amplifier.

We have measured the optical dephasing time of Er(3+) transitions near 1.5 microm in the two crystallographically inequivalent sites of Y(2)SiO(5), using an external-cavity diode laser amplified by an erbium-doped fiber amplifier. Two-pulse photon echoes were observed at zero field and in magnetic fields up to 55kG, with dephasing times as long as 580 micros (corresponding to a linewidth of 550 Hz). Stimulated echoes were also measured and showed evidence of spectral diffusion during the 13-ms lifetime of the (4)I(13/2) level.

Optical dephasing mechanisms in Tm(3+):Y(2)Si(2)O(7).

Optical dephasing measurements are reported for Tm(3+):Y(2)Si(2)O(7) as a function of temperature and laser excitation intensity. By use of photon echoes, a coherence time of T(2) = 23 micros was measured at 1.24 K for the (3)H(6)(1) ? (3)H(4)(1) transition at 790.427 nm, corresponding to a homogeneous linewidth of 14 kHz. The relatively broad inhomogeneous linewidth of 100 GHz gives an inhomogeneous-to-homogeneous linewidth ratio of Gamma(inh)/Gammah = 7 x 10(6). This large ratio, a transition wavelength suitable for GaAlAs semiconductor lasers, and the absence of hyperfine structure hole burning make this material a good candidate for time-domain signal processing and transient optically addressed data storage.