Disclosed are a mode-locked resonator according to an embodiment and an ultrashort pulse laser comprising the mode-locked resonator. The mode-locked resonator according to an embodiment includes a resonator including a shape of a sphere; and a saturable absorber coated on a surface of the resonator, wherein the resonator is coupled with some photons traveling in a tapered optical fiber disposed near the mode-locked resonator and interacts with the saturable absorber based on a Whispering Gallery Mode (WGM).

An electro-optic (EO) sensor and a method for detecting a local electric field strength, the EO sensor including: a first optical cavity; a gain medium within the first optical cavity; a mode locking element within the first optical cavity; and an EO material within the first optical cavity, an effective optical path length of the EO material being variable depending on the local electric field strength at the EO sensor, wherein the gain medium, the mode locking element, and the EO material are arranged in a common path of light within the first optical cavity, and wherein during operation, the EO sensor emits pulses of light at a repetition rate characteristic of an effective optical path length of the light within the first optical cavity, the effective optical path length varying depending on the electric field strength local to the EO sensor.

The present disclosure provides a method of optimising an optical system of a mode-locked laser oscillator or a regenerative, multi-pass or single pass amplifier. The method may include the steps of identifying crystallographic axes of an active laser gain medium crystal, cutting the crystal, and orienting the crystal in the optical system in a predetermined orientation relative to a propagation vector of a laser pulse depending on the required output of the optical system.

A laser device with a ring laser resonator includes a polarization maintaining (PM) fiber, a first quarter waveplate, and an optical isolator. The PM fiber has a light input end and a light output end and is configured to guide a first linearly polarized light with a first phase along a fast axis of the PM fiber from the light input end and a second linearly polarized light with a second phase along a slow axis of the PM fiber from the input end. The first quarter waveplate is disposed at the light output end of the PM fiber and configured to convert the first and the second linearly polarized lights into left-handed and right-handed (or right-handed and left-handed) circularly polarized lights, respectively. The optical isolator is configured to unidirectionally transmit a laser pulse in the ring laser resonator.

A two-dimensional semiconductor saturable absorber mirror comprises an optical fiber, a two-dimensional semiconductor thin film attached to an end surface of the optical fiber, and a gold film attached to the two-dimensional semiconductor thin film. A method for fabricating the two-dimensional semiconductor saturable absorber mirror comprises the following steps: cutting the optical fiber, putting the cut optical fiber and a two-dimensional semiconductor target into a vacuum chamber, ionizing a surface of two-dimensional semiconductor target to generate two-dimensional semiconductor plasma, depositing the two-dimensional semiconductor plasma on an exposed end surface of the optical fiber to form the two-dimensional semiconductor thin film, and by controlling deposition time and/or deposition temperature, ensuring the two-dimensional semiconductor thin film to be a desired thickness; and plating the gold film on the resulting two-dimensional semi-conductor thin film.

The invention relates to a method for manufacturing mirrors with saturable semiconducting absorptive material, which includes: depositing a saturable semiconducting absorptive material (205) onto a growth substrate (200) in order to form a structure; depositing at least one metal layer onto the structure such as to form a first mirror (211); and depositing a heat-conductive substrate (212) onto the metal layer by electrodeposition through an electrically insulating mask (312), allowing the selective deposition of the thermally conductive substrate, in order to predefine the perimeter of the mirrors with saturable semiconducting absorptive material.

A mid-infrared cascading fiber amplifier device having a source configured to generate a first electromagnetic wave output at a first frequency, a fiber coupled to the source and a pump coupled to the fiber and configured to generate a second electromagnetic wave output at a second frequency, wherein the second frequency is higher than the first frequency and causes the fiber to undergo two or more transitions in response to stimulation by the first electromagnetic wave output at the first frequency, wherein the first transition generates the first electromagnetic wave output approximately at the first frequency and the second transition generates the first electromagnetic wave output approximately at the first frequency.

A mode locking device is disclosed for altering repetition rate in a mode-locked laser. In an example device, laser light is coupled from a fiber into a cavity through a sliding pigtail collimator with a diameter selected such that it is a close tolerance fit with a female snout on a package. A lens focuses laser light to an appropriate spot size onto a SAM or SESAM, such that back-reflection into the fiber is maximized. A piezoelectric transducer is mounted in cooperation with the SAM or SESAM for cavity tuning.

The invention relates to a microchip laser having a monolithic resonator (1) which has a birefringent laser crystal (2), wherein a laser beam (9) decoupled from the resonator, (1) which has a laser wavelength, exits the resonator (1) along a laser beam axis (12) and the length (L) of the resonator (1) is less than 150 m based on a direction of the laser beam axis (12). The laser crystal (2) has a thickness (D) based on the direction of the laser beam axis (12) such that, in the case of a light beam (16) having the laser wavelength occurring in the direction of the laser beam axis (12) being incident on the laser crystal (2) between the ordinary and extraordinary beam (17, 19), in which the light beam (16) is divided in the laser crystal (2), a phase shift in the range of /2+//4 occurs in a single pass through the laser crystal (2).

A surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.