Intracavity Acousto-optic Tunable Filter Research Articles

Electronically tunable thulium-holmium mode-locked fiber laser for the 1700-1800 nm wavelength band.

We demonstrate a widely tunable, mode-locked fiber laser capable of producing sub-picosecond pulses between 1705 and 1805 nm. The 100 nm tuning range is achieved by using intracavity acousto-optic tunable filter. The laser delivers highly stable pulses via self-starting hybrid mode-locking triggered by frequency-shifting and nonlinear polarization evolution.

Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser.

We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a four-mirror ring cavity. By tuning of the fiber-laser wavelength over 33 nm through an intracavity acousto-optic tunable filter, the OPO idler wavelength is tuned from 3160 to 3500 nm in 330 micros, corresponding to an idler frequency-tuning speed of 28 THz/ms. At a fiber-laser power of 6.6 W at 1074 nm, the singly resonant OPO generates 1.13-W cw idler radiation at 3200 nm.

Difference-Frequency Generation in MgO-Doped Periodically Poled LiNbO3 Using an Electronically Tuned Ti:Sapphire Laser in Dual-Wavelength Operation

Tunable mid-infrared radiation was generated by difference-frequency generation in MgO-doped periodically poled LiNbO3 crystal by mixing of dual-wavelength pulses emitting from a Ti:sapphire laser, which was tuned with an intracavity acousto-optic tunable filter. A tuning range from 3.6 to 5.6 µm was obtained without any mechanical rotation of the nonlinear optical crystal and other laser elements.

Frequency structure in an electronically tuned Ti:sapphire laser:?periodic appearance of static fringes in both homodyne and heterodyne Michelson interferometers

Static interference fringes were observed repeatedly with changes of path difference in both homodyne and heterodyne Michelson interferometers. This unique coherence property of an electronically tuned Ti:sapphire laser with an intracavity acousto-optic tunable filter (AOTF) has revealed the frequency structure and dynamics of the laser field. The fact that static interference occurred in a heterodyne interferometer with unequal path lengths indicates backscattering of the intracavity laser field, suggesting that Brillouin-enhanced four-wave mixing occurs in the intracavity AOTF.

Widely tunable, narrow-linewidth, subnanosecond pulse generation in an electronically tuned Ti:sapphire laser

Widely tunable subnanosecond Ti:sapphire laser radiation pumped with a cw Q -switched laser-diode-pumped Nd:YAG laser has been demonstrated in a simple laser system with a configuration of variable cavity length. Laser wavelengths can be continuously tuned by adjustment of the rf of an intracavity acousto-optic tunable filter with a computer through the whole range of the laser gain. During tuning of the whole spectral range, there is no need to realign any optics in the laser, except for moving the mirror to track the change of the rf. The peak powers of the output pulses at a pump level of 300 mW are comparable with those of conventional tunable picosecond Ti:sapphire lasers at a cw pump level of almost 10 W.

Wavelength-swept fiber laser with frequency shifted feedback and resonantly swept intra-cavity acoustooptic tunable filter

This paper concerns a wavelength-swept fiber laser (WSFL) incorporating frequency shifted feedback and an intracavity passband filter, in which the wavelength of the modeless output is linearly, continuously and repeatedly tuned (in time) over a given range by modulation of the filter peak wavelength and filter strength. We show both numerically and experimentally that amplifier noise plays a key role in determining the operation of frequency-shifted fiber laser systems and that a "noisy" amplifier can be used to suppress the natural tendency of such lasers to pulse, allowing for continuous wave, modeless operation. Furthermore, we show that significant narrowing of a WSFL instantaneous swept linewidth can be obtained if the filter peak transmission wavelength is resonantly swept so as to follow the wavelength shift per pass due to the acoustooptic frequency shift. Using these ideas we go on to demonstrate and characterize a high-power diode-driven Er/sup 3+//Yb/sup 3+/ WSFL incorporating a bulk-optic acoustooptic tunable filter (AOTF). Linewidths as narrow as 9 GHz, sweep ranges up to 38 nm and output powers as high as 100 mW are obtained. Furthermore, we demonstrate the generation of user definable average spectral output by synchronous modulation of the filter strength and multiwavelength pulsed output at higher sweep rates. Excellent agreement between the experimental results and those of the numerical modeling is obtained. Our simulations show that reduced linewidth (<0.02 nm) and improved scan linearity should be readily achievable with realistic system improvements. We believe such sources to be of considerable physical and practical interest, with applications ranging from sensor array monitoring and device characterization through to low-coherence interferometry.