Abstract: Apparatus for providing optical radiation (15), which apparatus comprises an optical input (13), a coupler (2), a first semiconductor amplifier (3), a controller (4), a preamplifier (61), a power amplifier (62) and an output fibre (5), wherein: the optical input (13) is for receiving input optical radiation (14); the optical input (13) is connected in series to the coupler (2), the first semiconductor amplifier (3), the preamplifier (61), the power amplifier (62), and the output fibre (5); the apparatus being characterized in that: the first semiconductor amplifier (3) comprises a waveguide (6) having a low reflecting facet (8); the first semiconductor amplifier (3) is in a double pass configuration such that the low reflecting facet (8) is connected to both the optical input (13) and the preamplifier (61) via the coupler (2); and the controller (4) is configured to cause the waveguide (6) of the first semiconductor amplifier (3) to operate in saturation thereby enabling the first semiconductor amplifier (3)

Abstract: Apparatus for providing optical radiation (15), which apparatus comprises an optical input (13), a coupler (2), a first semiconductor amplifier (3), a controller (4), a preamplifier (61), a power amplifier (62) and an output fibre (5), wherein: the optical input (13) is for receiving input optical radiation (14); the optical input (13) is connected in series to the coupler (2), the first semiconductor amplifier (3), the preamplifier (61), the power amplifier (62), and the output fibre (5); the apparatus being characterized in that: the first semiconductor amplifier (3) comprises a waveguide (6) having a low reflecting facet (8); the first semiconductor amplifier (3) is in a double pass configuration such that the low reflecting facet (8) is connected to both the optical input (13) and the preamplifier (61) via the coupler (2); and the controller (4) is configured to cause the waveguide (6) of the first semiconductor amplifier (3) to operate in saturation thereby enabling the first semiconductor amplifier (3)

Abstract: A pulse conditioning apparatus can comprise a signal splitter for splitting a pulsed input signal into first and second pulsed signals; a spectrally dispersive element configured for subjecting the first pulsed signal to a spectral dispersion for compressing or stretching the first pulsed signal, the first and second pulsed signals being subjected to substantially different spectral dispersion; and a combiner for combining the first and second pulsed signals to an output pulsed signal, the output pulsed signal output comprising pulses having a surge pulse portion and a base pulse portion, at least one of the portions derived at least in part from the spectral dispersion and attendant compression or stretching of the first pulsed signal.

Abstract: A pulsed fiber laser apparatus for outputting picosecond laser pulses can comprise a fiber delivered pulsed seed laser for providing picosecond optical seed pulses, and at least one optical fiber amplifier in optical communication with the fiber delivered pulsed seed laser. The optical fiber amplifier can comprise a gain optical fiber that receives and optically amplifies picosecond optical pulses by operating in a nonlinear regime wherein the picosecond optical pulses can be spectrally broadened by a factor of at least 8 during amplification thereof. The apparatus can further comprise a pulse compressor apparatus in optical communication with the optical fiber amplifier for providing compressed picosecond optical pulses.

Abstract: A modelocked laser for generating pulses comprises a laser cavity, wherein the laser cavity comprises a length of hollow core fiber and wherein the length of hollow core fiber is such that the laser cavity supports a repetition rate of the generated pulses below 5 MHz.

Abstract: A method of tuning the time duration of laser output pulses, the method including spectrally dispersing optical pulses and further comprising providing an optical pulse having a time duration and a spectral bandwidth; spectrally dispersing (243, 245) the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse; outputting (226) an optical output pulse having a first time duration that is responsive to the selected change in time duration; providing another optical pulse; changing the amount of spectral bandwidth of the another optical pulse (272) to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change; and outputting (226) another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration o

Abstract: A pulsed fiber laser apparatus for outputting picosecond laser pulses can comprise a fiber delivered pulsed seed laser for providing picosecond optical seed pulses, and at least one optical fiber amplifier in optical communication with the fiber delivered pulsed seed laser. The optical fiber amplifier can comprise a gain optical fiber that receives and optically amplifies picosecond optical pulses by operating in a nonlinear regime wherein the picosecond optical pulses can be spectrally broadened by a factor of at least 8 during amplification thereof. The apparatus can further comprise a pulse compressor apparatus in optical communication with the optical fiber amplifier for providing compressed picosecond optical pulses.

Abstract: A method of tuning the time duration of laser output pulses, the method including spectrally dispersing optical pulses and further comprising providing an optical pulse having a time duration and a spectral bandwidth; spectrally dispersing (243, 245) the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral band-width of the pulse; outputting (226) an optical output pulse having a first time duration that is responsive to the selected change in time duration; providing another optical pulse; changing the amount of spectral bandwidth of the another optical pulse (272) to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change; and outputting (226) another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration

Abstract: A method of tuning the time duration of laser output pulses, the method including spectrally dispersing optical pulses and further comprising providing an optical pulse having a time duration and a spectral bandwidth; spectrally dispersing (243, 245) the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse; outputting (226) an optical output pulse having a first time duration that is responsive to the selected change in time duration; providing another optical pulse; changing the amount of spectral bandwidth of the another optical pulse (272) to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change; and outputting (226) another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration o