A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.

A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.

Free-space optical (FSO) wireless transmission, including optical communications, remote-sensing, power beaming, etc., can be enhanced by replacing conventional laser sources that operate in the infrared portion of the optical spectrum with ultra-short pulsed laser (USPL) sources having peak pulse powers of one kWatt or greater and pulse lengths of less than one picosecond. Specifically, it has been observed that under these conditions the attenuation of an USPL beam having the same average optical power as a conventional laser in a lossy medium, such as the atmosphere, is substantially less than the attenuation of a conventional laser beam having a lower peak pulse power and/or a longer pulse width. The superior system performance when using an USPL can be translated into an increased distance between a laser source in a transmitter and a photodetector in receiver and/or a higher reliability of system operation in inclement weather conditions.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

A method for intracavity frequency conversion includes end-pumping a solid-state gain medium in a laser resonator with a pump laser beam to generate an intracavity laser beam circulating in the laser resonator, and frequency-converting a portion of the intracavity laser beam in a nonlinear crystal, located in the laser resonator, to generate a frequency-converted laser beam. The method controls the output power and at least one output beam parameter of the frequency-converted laser beam by adjusting (a) the pump power and (b) a resonator loss imposed on the intracavity laser beam. Taking advantage of both the pump laser beam and the intracavity laser beam contributing to thermal lensing in the gain medium, this control scheme is capable of controlling the output power and the output beam parameter(s) independently of each other.

A method for intracavity frequency conversion includes end-pumping a solid-state gain medium in a laser resonator with a pump laser beam to generate an intracavity laser beam circulating in the laser resonator, and frequency-converting a portion of the intracavity laser beam in a nonlinear crystal, located in the laser resonator, to generate a frequency-converted laser beam. The method controls the output power and at least one output beam parameter of the frequency-converted laser beam by adjusting (a) the pump power and (b) a resonator loss imposed on the intracavity laser beam. Taking advantage of both the pump laser beam and the intracavity laser beam contributing to thermal lensing in the gain medium, this control scheme is capable of controlling the output power and the output beam parameter(s) independently of each other.

Provided are a high-energy and high-powered laser light source and a photoemission electron microscope using the laser light source. The laser light source 2 is intended for use in the photoemission electron microscope for emitting a quasi-continuous wave laser 7 and includes: a first laser light source 100 configured to emit a continuous wave coherent light 100a, an optical resonator 110 including an optical path in which the continuous wave coherent light 100a circulates and including a non-linear optical element 114 disposed on the optical path, and a quasi-continuous wave light source 120 configured to emit a quasi-continuous wave coherent light 120a having a wavelength shorter than that of the continuous wave coherent light 100a and having a near rectangular output waveform. When the quasi-continuous wave coherent light 120a is incident on the non-linear optical element 114 from outside the optical resonator 110 while the continuous wave coherent light 100a is entering the optical resonator 110 to circulate in the optical path, the quasi-continuous wave laser 7 having a wavelength shorter than that of the quasi-continuous wave coherent light 120a is emitted from the non-linear optical element 114.