Passively mode-coupled femtosecond laser

Passive mode locked femtosecond laser having a ring resonator comprising:

• a laser-active element having a group velocity dispersion;
• at least one dielectric mirror having a negative group velocity dispersion (GVDη) for reflection;
• two concave mirrors which are spatially arranged immediately adjacent to the laser-active element and are oriented with their concave surfaces towards the laser-active element;
• and an optical output coupler;
• wherein the ring resonator has an optical path and each of said laser-active element and mirrors is arranged along the optical path, and
• wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the value of the positive group velocity dispersion associated with the laser active element,
• characterized in that
• the optical path of the resonator is below 60 cm, and
• the focus length of each of the concave mirrors which are arranged immediately adjacent to the laser-active element is below 3 cm,
• whereby a high repetition generation of femtosecond pulses is attainable.

A method for obtaining a generation of femtosecond pulses from and turning a passive mode locked femtosecond laser having a ring resonator comprising a laser-active element having a group velocity dispersion, a prismatic element having a group velocity dispersion, at least one dielectric mirror having a negative group velocity dispersion (GVDη) for reflection, two concave mirror which are spatially arranged immediately adjacent to the laser-active element and are oriented with respective concave surfaces towards the laser-active element, and an optical output coupler, wherein the ring resonator has an optical path and each of said laser-active element, prismatic element and mirrors is arranged along the optical path, and wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the combined value of the positive group velocity dispersion associated with the laser active element and the prismatic element, characterized in that the optical path of the resonator is below 120 cm, the focus length of each of the concave mirrors, which are arranged adjacent next to the laser-active element is below 3 cm, where

• in a first step a high repetition generation of femtosecond pulses is obtained and
• in a second step one of (i) said at least one dielectric mirror or (ii) the output coupler or (iii) a further mirror is tiltable at a tilt angle upon an axis wherein by adjusting the tilt angle in interplay with the spatial dispersion of the prismatic element, a wavelength is adjusted for which the resonator supports laser activity.

Passive mode coupled femtosecond laser having a ring resonator comprising:

• a laser-active element having a group velocity dispersion;
• two concave mirrors which are spatially arranged immediately adjacent to the laser-active element and are oriented with their concave surfaces towards the laser-active element;
• at least one dielectric mirror receiving a reflection from at least one of said concave mirror, having a negative group velocity dispersion for reflection and wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the value of the positive group velocity dispersion associated with the laser active element;
• and
• an optical output coupler receiving a reflection from at least one of said at least one concave mirror and dielectric mirror,
• whereby a high repetition generation of femtosecond pulses is obtained.

Passive mode coupled femtosecond laser having a ring resonator comprising:

• a laser-active element having a group velocity dispersion,
• two concave mirrors which are spatially arranged immediately adjacent to tee laser-active element and are oriented with their concave surfaces towards the laser-active element;
• at least one dielectric mirror, having a negative group velocity dispersion for reflection and wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the value of the positive group velocity dispersion associated with the laser active element;
• and
• an optical output coupler,
• wherein the ring resonator has an optical path and each of said laser-active element, mirrors and coupler is arranged along the optical path, and
• whereby a high repetition generation of femtosecond pulses is obtained.

Passive mode coupled femtosecond laser having a ring resonator comprising:

• a laser-active element having a group velocity dispersion;
• a prismatic element having a group velocity dispersion,
• two concave mirrors which are spatially arranged immediately adjacent to the laser-active element and are oriented with their concave surfaces towards the laser-active element;
• at least one dielectric mirror, having a negative group velocity dispersion for reflection and wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the value of the positive group velocity dispersion associated with the laser active element;
• and
• an optical output coupler,
• wherein the ring resonator has an optical path and each of said laser-active element, mirrors and coupler is arranged along the optical path, and
• whereby a high repetition generation of femtosecond pulses is obtained, and one of said at least one dielectric mirror, output coupler, or a further mirror is tiltable at a tilt angle upon an axis wherein by adjusting the tilt angle in interplay with the spatial dispersion of the prismatic element, a wavelength is adjusted for which the resonator supports laser activity.

Passive mode coupled femtosecond laser having a ring resonator comprising:

• a laser-active element having a group velocity dispersion;
• two concave mirrors which are spatially arranged immediately adjacent to the laser-active element and are oriented with their concave surfaces towards the laser-active element;
• at least one dielectric moor receiving a reflection from at least one of said concave mirror, and a prismatic element receiving a reflection from the at least one dielectric mirror, wherein the at least one dielectric mirror has a negative group velocity dispersion for reflection and wherein for a contiguous part of the optical spectrum capable of being amplified by the laser-active element, the value of the negative group velocity dispersion associated with the at least one dielectric mirror is greater than the combined value of the positive group velocity dispersion associated with the laser active element and at least one prismatic element;
• and
• an optical output coupler receiving a reflection from at least of one of said concave mirror and at least one dielectric mirror,
• whereby a high repetition generation of femtosecond pulses is obtained, and one of said at least one dielectric mirror, output coupler, or a further mirror is tiltable at a tilt angle upon an axis wherein by adjusting the tilt angle in interplay with the spatial dispersion of the prismatic element, a wavelength is adjusted for which the resonator supports laser activity.