Electroholographic Tunable Laser

Ph.D. Student: Sagi Frishman

The electroholographic (EH) tunable laser is a laser whose wavelength of operation can be tuned over a wide spectral range by means of intracavity EH dispersive element.

The latter is a an EH grating operated in the g44 configuration which provides electrical tunability at low operating voltages [REF17] with sub nanosecond switching time [REF12].

The first experimental demonstration of the EH tunable laser was a fiber loop in which  an erbium doped fiber amplifier (EDFA) was connected in series with a g44 EH grating constructed in a KLTN crystal. This is illustrated schematically in Figure 1. Electrical tunability over the entire C-band was demonstrated.  Details of this demonstration are given in [REF10].

Figure 1: Schematic illustration of the first experimental demonstration of the electroholographic tunable laser.

In principle, an EH grating implemented in a KLTN crystal can be operated in the spectral range  400 nm - 5000 nm where the crystal is transparent. This provides wavelength tunability throughout the VIS-NIR spectral range.

Our current effort is to develop an EH tunable laser in a waveguide architecture employing refractive index engineering as the fabrication methodology. Using a semiconductor optical amplifier as the gain medium will enable switching between wavelengths within less than 10 nanoseconds.