An optical element has a design wavelength , an optical axis and alternating refractive index changes along the optical axis. The alternating refractive index changes form three reflectors and two optical resonators for light of the design wavelength incident along the optical axis, wherein each of the resonators is arranged between two of the reflectors. At least one of the resonators includes a Kerr-active material; and the two optical resonators differ with regard to non-linear components I.sub.Res(i).Math.n.sub.2(i) of their total refractive indices n(i)=n.sub.0(i)+I.sub.Res(i).Math.n.sub.2(i) by at least 50% of the smaller one of the non-linear components in terms of absolute value, wherein I.sub.Res(i) is a resulting intensity of the light of the design wavelength that results within the respective resonator due to its arrangement between the respective reflectors, and wherein n.sub.2(i) is a non-linear refractive index of the respective resonator.

The present disclosure relates to a device and a method for adjusting a pulse width of a laser beam by using the plasma generated by being induced from laser as a shutter, and more particularly, to a device and a method for adjusting a laser pulse width, which can precisely and quickly adjust the laser pulse width by dividing the laser generated from a laser light source into a target pulse and a shutter pulse; converting the optical path of the divided laser; and chopping the target pulse by using the plasma induced from the shutter pulse as an optical shutter in a cell having adjustable internal pressure.

Methods, apparatus, and systems for active saturable absorbance of an optical beam. An active saturable absorber may comprise an optical input to receive an optical beam, and one or more lengths of fiber between the optical input and an optical output. At least one of the lengths of fiber comprises a confinement region that is optically coupled to the output. The active saturable absorber may further comprise an optical detector to sense a characteristic of the optical beam, such as power. The active saturable absorber may further comprise a perturbation device to modulate, through action upon the one or more lengths of fiber, a transmittance of the beam through a fiber confinement region from a lower transmittance level to a higher transmittance level based on an indication of the characteristic sensed while the transmittance level is low.

According to some aspects, a transmissive and all-dielectric optical component/limiter with great cutoff efficiency using Vanadium Dioxide (VO.sub.2) as the active component is disclosed. In some embodiments, Vanadium dioxide is used for an optical limiter due to the large contrast in optical constants upon undergoing the semiconductor to metal phase transition. When triggered optically, this transition occurs within 60 fs, making the device suitable for an ultrafast laser environment. In addition, the phase transition threshold is tunable by applying stress or doping; therefore, the device cutoff intensity can be adjusted to fulfill specific requirements.

The present disclosure provides a waveguide integrated optical modulator, which is made of a bismuth film, an antimony film, or a tellurium film. A thickness of the bismuth film, the antimony film, or the tellurium film is between 10 nm and 200 nm, and the bismuth film, the antimony film, or the tellurium film is produced by physical vapor deposition method. The waveguide integrated optical modulator can directly add the symmetrical electrode on the surface of the bismuth film, the antimony film, or the tellurium film, and apply an external bias voltage of different amplitudes to the bismuth film, the antimony film, or the tellurium film by adjusting the power source. Thus, the waveguide integrated optical modulator can actively control the nonlinear optical characteristics of the saturable absorber by changing the magnitude of the external voltage, and further actively modulate the laser characteristics of the pulse.

The present disclosure discloses a saturable absorber mirror of a composite structure, including: a substrate; a buffer layer on the substrate; a distributed Bragg reflective mirror on the buffer layer; a quantum dot or quantum well saturable absorber body on the distributed Bragg reflective mirror; a graphene saturable absorber body on the quantum dot or quantum well saturable absorber body. In the present disclosure, the graphene saturable absorber body is composited with the quantum dot saturable absorber body or the quantum well saturable absorber body to be used as the saturable absorber body in the saturable absorber mirror of the present disclosure. A thermal damage threshold and an optical property stability of the saturable absorber body are improved, and an ultrafast laser pulse with high power and short pulse mode locking, a stable output repetition cycle, a narrow pulse width, and a short response time is implemented.

A light absorption material includes a compound represented by the following formula (1) as a main component:

##STR00001##

In the formula (1), R.sup.1 to R.sup.14 each independently include at least one atom selected from the group consisting of H, C, N, O, F, P, S, Cl, I, and Br, and n is an integer greater than or equal to 2.

Embodiments are directed to a method for directly synthesizing graphene on a surface of a target object, which includes: forming a non-metal layer on a support substrate; disposing the target object in a space above the support substrate, which is opposite to the non-metal layer; and injecting a carbon precursor to form graphene on the surface of the target object to synthesize a graphene film, wherein the graphene is nucleated and grown by a decomposition of the carbon precursor, the carbon precursor is decomposed by heat with the catalytic assist from the non-metal layer, a carbon atom from the decomposition of the precursor is anchored on the surface to form the graphene film.

An optical structure comprising at least one stack having a central filter (1) and two sandwiching optical elements (2,3) between which the central filter (1) is interposed, wherein the central filter (1) is in a matrix material. The matrix material being doped with at least one doping agent, the central filter (1) and the two optical elements (2,3) on either side thereof being assembled by bonding layers (4a, 4b) of a material based on the same matrix material as that of the central filter, the optical elements (2,3) on either side of the central filter (1) and the bonding layers (4a, 4b) each having a refractive index equal to that of the material of the central filter or only differing from this refractive index within a range of plus or minus 0.05, preferably within a range of plus or minus 0.02.

The present invention relates to a method of manufacturing large area graphene for graphene-based photonics devices such as bolometric graphene detectors, or for use as a saturable absorber in ultra-high bandwidth detectors for producing ultrafast laser pulses. The method includes: growing a first graphene layer on one side of a metal substrate, and a second graphene layer on another side of the metal substrate; coating the first graphene layer with a plurality of resist layers including a low molecular weight polymethylmethacrylate, and a high molecular weight polymethylmethacrylate; removing the second graphene layer and the metal substrate to reveal the first graphene layer; disposing the first graphene layer on an optical substrate; and removing the plurality of resist layers from the first graphene layer to reveal a final graphene layer, which can be used as the basis to manufacture a multilayer graphene structure for graphene detectors.