P.J. Bennett

A PHOTONIC SWITCH BASED ON A GIGANTIC, REVERSIBLE OPTICAL NONLINEARITY OF LIQUEFYING GALLIUM

Liquefying gallium shows a huge reversible optical nonlinearity which is compatible with waveguide technology and promises to be a breakthrough in broadband, light-by-light modulation at milliwatt operating power levels and frequency band spanning up to several hundred kilohertz.

Cubic optical nonlinearity of free electrons in bulk gold

A fast (Tau(response) <90 fs) free-electron spin-f lipping frequency-degenerate nonlinearity with a signif icant value of|chi((3))(xxyy)(omega,omega,omega,-omega)chi((3))(xxyy)(omega,omega,omega,-omega)|~10(-)(8)esu has been observed in bulk gold at 1260 nm by use of a new pump-probe polarization-sensitive technique.

Femtosecond cubic optical nonlinearity of thin nickel films

Transient pump-probe measurements of circular anisotropy in nickel films induced by 38-fs optical pulses show an instantaneous response that is related to the optical orientation of the spins of free electrons. Measurements in a sample of variable thickness, performed in both transmission and reflection, revealed that the surface significantly influences the degenerate cubic optical nonlinearity of the nickel films to a depth of approximately 4-5 nm into the bulk.

Femtosecond pulse duration measurements utilizing an ultrafast nonlinearity of nickel

A new, broadband, background free autocorrelation technique for measuring pulse durations of visible and infrared femtosecond laser pulses is described. The technique is based on the use of a reflective polarization-sensitive interaction in metallic nickel.

Nonreciprocity of natural rotatory power

We have observed that a light beam that passed through an optically active crystal of Bi(12)SiO(20) and that was then ref lected exactly back through it did not recover its initial polarization orientation. The nonreciprocal component of the rotation was of the order of 2 x 10(-3) of the reciprocal, single-pass rotation. This nonreciprocity is unambiguous evidence of broken reversality of the light-matter interaction process.

Cubic optical nonlinearities of metals in the vicinity of the melting point

Abstract We report the first study of frequency degenerate cubic optical nonlinearities in bulk metals across the melting point. Using pump–probe reflectivity and precise pump–probe polarimetry a strong femtosecond electronic nonlinearity (X (3) ≈ 10−8 esu) has been observed in indium. The effective nonlinearity sharply increases when the temperature approaches the melting point. We also report the results of a study on the nonlinearity of nickel films and discuss the effect of an interface with glass on the magnitude and sign of the nonlinearity.

Ultrafast cubic optical nonlinearity in semitransparent nickel films: Bulk versus surface contributions

Summary form only given. We report the results of a study of semitransparent films of nickel of varying thickness using femtosecond time-resolved polarimetry. For the first time we have combined transmission and reflection measurements, and have studied glass and air interfaces of nickel films of different thicknesses. We have identified importance of the surface contribution to the film nonlinearity, and have also observed that not only the magnitude of the cubic nonlinearity in nickel, but even its sign could be different depending on the nature of the interface. We also saw that both bulk and surface components of the cubic optical nonlinearity in nickel films are exceptionally fast with relaxation times shorter than /spl sim/40 fs.

Nonlinearity of liquefying gallium: controlling light with light at milliwatt power levels

We have recently demonstrated that the reflectivity of a metallic gallium-glass interface shows a strong change and a noticeable hysteresis in the melting-cooling cycle and that such hysteresis can be considerably modified by continuous wave optical stimulation at intensities of a few kW/cm/sup 2/. Here we demonstrate that the nonresonant nonlinear mechanism is fully reversible with a fast recovery time. This nonlinearity has been used to achieve a truly practical all-optical switching with milliwatt switching powers, submicrosecond response times, which could be used from visible to IR spectral regions.