Abstract: The invention is a double chirped mirror and a method of constructing a double chirped mirror for a frequency range of electromagnetic radiation, comprising specifying a design including a plurality of layers, the plurality of layers being transparent to the electromagnetic radiation and having refractive indices which vary between layers in the plurality of layers, and wherein for a first set of layers the optical thickness of alternate layers in the set of layers varies monotonically and the total optical thickness of a layer and the two adjacent half layers in the set of layers varies monotonically. The design is optimized by adjusting the optical thickness of layers in the plurality of layers.

Abstract: The invention is a double chirped mirror and a method of constructing a double chirped mirror for a frequency range of electromagnetic radiation, comprising specifying a design including a plurality of layers, the plurality of layers being transparent to the electromagnetic radiation and having refractive indices which vary between layers in the plurality of layers, and wherein for a first set of layers the optical thickness of alternate layers in the set of layers varies monotonically and the total optical thickness of a layer and the two adjacent half layers in the set of layers varies monotonically. The design is optimized by adjusting the optical thickness of layers in the plurality of layers.

Abstract: The dielectric and/or semiconductor device influences the dispersion of electromagnetic radiation within a given spectral range. It comprises a substrate being essentially transparent to said electromagnetic radiation. The substrate has a first surface for incoupling said electromagnetic radiation into said substrate, and a second surface. The device further comprises a reflective multilayer structure on said second surface, said multilayer structure providing a controlled dispersion characteristic upon reflection of said electromagnetic radiation, e.g., a chirped mirror. The device is arranged in such a way that there is essentially no interference of electromagnetic radiation propagating in the direction of said multilayer structure and electromagnetic radiation reflected by said multilayer structure. An antireflection coating may be provided on the first surface of the substrate. With this device, oscillations in the group delay dispersion can almost completely be avoided.

Abstract: The advantages of both active and passive modelocking techniques are realized within a single device by providing a p-i-n modulator formed at antiresonance within a Fabry-Perot etalon. The p-i-n modulator actively modulates light within the laser cavity by introducing periodic loss in response to changing voltages applied to the modulator. The p-i-n modulator includes an intrinsic region that is disposed between a p-doped region and an n-doped region. The modelocking performance of the p-i-n modulator is enhanced by the saturable absorber action of the intrinsic region.

Abstract: Extended wavelength tunability is achieved in a saturable absorber for applications such as modelocking lasers by realizing a semiconductor structure having a tapered energy bandgap profile in a portion of the saturable absorber wherein the profile is given as a function of the distance along the propagation axis of the saturable absorber. For certain applications, at least one mirror is monolithically integrated with the saturable absorber.

Abstract: Saturation intensity and loss of a saturable absorber are substantially independently regulated by positioning the saturable absorber element within a Fabry-Perot etalon defined by first and second reflective elements so that the saturable absorber element responds to light at optical wavelengths in the anti-resonant portion of the Fabry-Perot spectral response, that is, between optical wavelengths corresponding to resonance peaks. The resulting combination of elements is called a Fabry-Perot saturable absorber. Thickness of the saturable absorber element substantially sets the loss of the Fabry-Perot saturable absorber while changes in the reflectivity of the first reflective element onto which the light is incident substantially determines the saturation intensity (degree of nonlinearity) and assists in compensating loss of the saturable absorber element.

Abstract: Modelocking of a solid state laser such as a Ti:Al.sub.2 O.sub.3 laser is achieved by employing an external cavity defined by spatially separated reflective elements wherein at least one of the reflective elements exhibits a nonlinear characteristic in response to an impinging light beam. Exemplary nonlinear reflective elements are described using bulk semiconductor material or semiconductor quantum well structures integrated with a rear reflector such as a stack of quarter-wave thick dielectric or semiconductor material. Tuning control of the nonlinear reflective element may be introduced with temperature control arrangements and with mechanical translation arrangements in conjunction with lateral band gap engineering of the semiconductor material.