Timothy J. Carrig

Continuous-wave broadly tunable Cr2+:ZnSe laser.

We report room-temperature operation of an all-solid-state broadly tunable continuous-wave Cr(2+):ZnSe laser. Output power of 250 mW, an absorbed power slope efficiency of 63%, and continuous tunability from 2138 to 2760 nm are demonstrated.

Mode-locked Cr 2+ :ZnSe laser

We describe active mode locking of a Cr(2+):ZnSe laser operating near 2.5 mum. The laser produces 4.4-ps transform-limited Gaussian-shaped pulses and produces 82 mW of average power.

Performance of a continuous-wave forsterite laser with krypton ion, Ti:sapphire, and Nd:YAG pump lasers

The authors characterize continuous-wave operation of a chromium-doped forsterite (Cr/sup 4+/:Mg/sub 2/SiO/sub 4/) laser using krypton ion, Ti:sapphire, and Nd:YAG lasers as pump sources. Measurements were made pumping at 647 nm and 676 nm with the krypton ion laser, between 690 and 1010 nm with the Ti:sapphire laser, and at 1.06 mu m with the Nd:YAG laser. Threshold pump powers and slope efficiencies are compared for output coupler transmissions varying between 1 and 15.5%. Room-temperature operation was only achieved using the Nd:YAG pump laser. Forsterite laser output power as a function of both temperature and pumping wavelength is discussed. >

Femtosecond pulse generation by using an additive-pulse mode-locked chromium-doped forsterite laser operated at 77 K

Using an acousto-optically mode-locked chromium-doped forsterite laser, operated at 77 K and coupled to a nonlinear resonator containing a single-mode fiber, we have produced femtosecond pulses of 150-fs duration at 1.23 microm with useful output powers of approximately 60 mW This represents what is to our knowledge the first demonstration of femtosecond pulse generation from this laser system using the coupled-cavity mode-locking scheme.

Tunable, cw operation of a multiwatt forsterite laser.

We have obtained over 1.8 W of power from a cw chromium-doped forsterite laser operated at 77 K when it is pumped by a 7.3-W Nd:YAG laser at 1.06 microm. The forsterite laser tunes smoothly from 1.2 to 1.32 microm. At room temperature the output power decreases to approximately 35% of the cryogenic power level.

Tunable infrared laser sources for DIAL

Broadly tunable infrared laser sources are of interest for a variety of applications including differential absorption lidar, differential scattering lidar, multi-spectral detection and imaging, hard target identification and discrimination, optical communications in poor visibility conditions, and spectroscopy. For chemical sensing applications, sources are particularly sought in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions. A variety of laser and nonlinear optical devices have been demonstrated that access these wavelengths. In particular, CTI is developing novel, tunable, narrow linewidth transmitters for coherent and direct detection lidar measurement applications. An example is a multi-watt Cr:ZnSe laser that is tunable over the 2.1 to 2.8 micrometers wavelength region. This laser has been used to pump-tune optical parametric oscillators (OPOs) that are broadly tunable across the MWIR and LWIR. We are also developing tunable Yb lasers that can be used to pump OPOs that emit signal beams in the eyesafe 1.55 micrometers region while generating idler beams that access the 3 to 4 micrometers MWIR band. This paper describes these sources.

Power scaling of Cr2+:ZnSe lasers

We describe continuous-wave, quasi-continuous-wave and gain-switched operation of moderate power Cr:ZnSe lasers. We have demonstrated CW output powers as high as 1.83 W, quasi-CW power of 3.6 W at 10% duty cycle, and 0.35 mJ gain- switched pulses at a repetition frequency of 1000 Hz.

Mode locked and Q-switched Cr:ZnSe laser using a Semiconductor Saturable Absorbing Mirror (SESAM)

A passively mode-locked cw Cr:ZnSe laser operating near 2.5 μm generated 400 mW of output power with 11 psec pulse duration and 100 MHz repetition rate using a Semiconductor Saturable Absorbing Mirror (SESAM). Adjusting the cavity to be significantly shorter and have a weaker focus on the SESAM, passive Q-switched operation could also be obtained with the same SESAM. Q-switched operation produced 50 nsec pulses with a 1 MHZ repetition rate, and peak powers of 10 W. In both mode-locked and Q-switched operation, the laser was pumped with 2.4W from a Tm:YALO laser.

Pulsed, room-temperature operation of a tunable NaCl color-center laser

A room-temperature, pulsed, color-center laser using OH(-)-doped NaCl crystals is reported. Crystals were transversely pumped by a Q-switched Nd:YAG laser at 1.06microm and produced output energies of 8.6 mJ in 20-nsec pulses. The tuning range extended from 1.37 to 1.77 microm. During 40 h of operation (>10(6) pulses), a gradual power fading was observed. Laser action is tentatively ascribed to F(2)(+) centers.

Chromium-doped chalcogenide lasers

This paper reviews fundamental material properties and the current state-of-the-art of continuous-wave and pulsed Cr/sup 2+/ doped chalcogenide lasers. Multi-watt output powers are demonstrated in both CW and pulsed modes of operation. Laser output and optical-to-optical conversion efficiency for a Cr:ZnSe laser operating at 7 kHz pulse repetition frequency are presented.