Single-frequency nanosecond fiber laser source
The Intensus-SF is a highly stable, long coherence length all-fiber laser system that can provide up to 10 watts average power of single-frequency pulse modulated 1550-nm signal. A single-frequency 4-ns pulse at 1550 nm at 5 W power (PRF=2 MHz) is shown in the photo above. The pulse duration of the I1f can be extended to 35 ns or reduced to below 2 ns. The pulse energy and power are extremely stable. Frequency doubling is an option (over 2 watts at 775nm with the 5W IR system). Wavelength extensions to the visible (516 nm) and the DUV (258 nm & 193 nm) are also available on a custom basis.
A special heterodyne analyzer was constructed at Actinix to detect the presence of chirp caused by self phase modulation (SPM) in the fiber power amplifier. The figure below shows the heterodyne beat note signals (2.2 GHz) measured on a fast oscilloscope, for operation at 0.5 watt (left) and 5 watts full power (right). A slight chirp is evident on right side of the 5 watt pulse, implying some self-phase modulation occurring at high power.
Frequency doubling options are available for the Intensus fiber systems. The second harmonic (SH) of the Intensus-1 fundamental infrared was generated, and is plotted below at different rep rates. The 1550-nm average power in all cases was approximately 5 watts. At 4 MHz (pulse energy = 1.25 micro-joules) 2 watts at 775 nm is attained. At 3 MHz (1.7 micro-joules per pulse) the average power rises to 2.5 watts. At 2 MHz (2.5 microjoules) the power is 2.7 watts.