An optical device includes first and second 45° Faraday rotators. A 45° polarizer is located between the first and second Faraday rotators such that light in a prescribed polarization state that is incident on the first 45° Faraday rotator traverses the first 45° Faraday rotator as well as the 45° polarizer and the second 45° Faraday rotator. In one implementation the optical device is operable to receive a light beam traveling in a first direction and output a light beam that is in a predetermined polarization state. Likewise, the optical device is operable to receive an unpolarized light beam traveling in a second direction opposite the first direction and outputs a light beam that is in a predetermined polarization state. The polarization state in which the two output beams are arranged may be the same or orthogonal to one another.

A figure-8 laser is configured in which gain in the uni-directional loop can be removed while maintaining mode-locked operation with gain only in the bi-directional nonlinear amplifying loop. Simplified self-starting and control over pulse characteristics by controlling gain in the bi-directional loop is made possible.

An integrated Ti:Sapphire laser device includes a substrate [100], a first waveguide resonator [102] composed of a gain medium integrated onto the substrate in a planar technology configuration, a frequency doubler [104] composed of a second order nonlinear material integrated onto the substrate in a planar technology configuration, and a second waveguide resonator [106] composed of a titanium doped sapphire gain medium integrated onto the substrate in a planar technology configuration.

Apparatus and methods for producing ultrashort optical pulses are described. A high-power, solid-state, passively mode-locked laser can be manufactured in a compact module that can be incorporated into a portable instrument. The mode-locked laser can produce sub-50-ps optical pulses at a repetition rates between 200 MHz and 50 MHz, rates suitable for massively parallel data-acquisition. The optical pulses can be used to generate a reference clock signal for synchronizing data-acquisition and signal-processing electronics of the portable instrument.

A nanoscale circuit has an optical antenna receiving the radiation from a mode-locked laser and it responds by transmitting selected microwave or terahertz frequencies with a separate orthogonal antenna. Only MIM diodes, low-pass filters, and a load resistor are used to generate, separate, and transmit at the harmonics of the laser pulse-repetition rate.

A laser system and method. In one example, the laser system includes an optical pulse stretcher configured to stretch pulse durations of an input train of input pulses to produce a train of stretched laser pulses, a pulse replicator module configured to increase a pulse repetition rate of the train of stretched laser pulses to produce a modified pulse train of laser light, a fiber power amplifier configured to amplify the modified pulse train to produce amplified laser pulses, and a pulse compressor that temporally compresses the amplified laser pulses to produce amplified and compressed laser pulses. The system may further include a nonlinear frequency conversion stage comprising at least one nonlinear crystal.

The present disclosure provides techniques for improving the rate and efficiency of charge transfer within an integrated circuit configured to receive incident photons. Some aspects of the present disclosure relate to integrated circuits that are configured to induce one or more intrinsic electric fields that increase the rate and efficiency of charge transfer within the integrated circuits. Some aspects of the present disclosure relate to integrated circuits configured to induce a charge carrier depletion in the photodetection region(s) of the integrated circuits. In some embodiments, the charge carrier depletion in the photodetection region(s) may be intrinsic, in that the depletion is induced even in the absence of external electric fields applied to the integrated circuit. Some aspects of the present disclosure relate to processes for operating and/or manufacturing integrated devices as described herein.

A method and apparatus for passively synchronising the repetition rate of two or more mode-locked lasers is described. The method and apparatus involve forming a first synchronising optical field (6) by separating a portion of an output field of a first mode-locked laser (2) and thereafter redirecting this synchronising optical field to form a driving signal for a second mode-locked laser (3). Employing these techniques results in systems with timing jitter of less than 1 fs. The method is independent of the wavelength and polarisation at which the mode-locked lasers operate and so is not limited to use with any particular type of mode-locked laser. Since the technique is passive it does not require the employment of electronics, variable time delay paths or additional non-linear optical crystals. Therefore, the method and apparatus are significantly less complex than those known in the art and are not power limited by additional non-linear optical processes. Part of the output (7) of the first mode-locked laser (2) is redirected via a beam splitter (9) and beam steering mirrors (11,12) and a half-wave plate (15) to a polariser (13) in the beam line of the second mode-locked laser (3). The seeding and synchronising signal from the first mode-locked laser (2) may be perpendicularly polarized with respect to the polarization of the second mode-locked laser (3) and may have a different wavelength.

Apparatus for modelocking a fiber laser cavity includes two variable retarder assemblies and a polarizing element. The variable retarder assemblies each have two electronically addressable elements and one fixed element. The first variable retarder assembly prepares a polarization state suitable for NPE modelocking to be launched into the fiber, and the second variable retarder assembly controls the polarization state after exiting the fiber, before being incident on the polarizing element. A control system controls the electronically addressable phase retarders in order to create and modify conditions for modelocking the fiber laser.

Embodiments relate to a polymer waveguide including a substrate, a cladding layer made of a first polymer, formed on the substrate, wherein a first monomer is polymerized into the first polymer, and the cladding layer has a groove for the waveguide by removing part of the cladding layer, and a core accommodating graphene therein, formed on the groove, a method for manufacturing the same, and a passively mode-locked laser based on the polymer waveguide.