Coherent Laser Systems Research Articles

Mid-Infrared Laser Generation of Zn1-xMnxSe and Zn1-xMgxSe (x ≈ 0.3) Single Crystals Co-Doped by Cr2+ and Fe2+ Ions-Comparison of Different Excitation Wavelengths.

Two different mid-infrared (mid-IR) solid-state crystalline laser active media of Cr, Fe:ZnMnSe and Cr, Fe:ZnMgSe with similar amounts of manganese or magnesium ions of x ≈ 0.3 were investigated at cryogenic temperatures for three different excitation wavelengths: Q-switched Er:YLF laser at the wavelength of 1.73 m, Q-switched Er:YAG laser at 2.94 m, and the gain-switched Fe:ZnSe laser operated at a liquid nitrogen temperature of 78 K at ∼4.05 m. The temperature dependence of spectral and laser characteristics was measured. Depending on the excitation wavelength and the selected output coupler, both laser systems were able to generate radiation by Cr or by Fe ions under direct excitation or indirectly by the Cr→ Fe energy transfer mechanism. Laser generation of Fe ions in Cr, Fe:ZnMnSe and Cr, Fe:ZnMgSe (x ≈ 0.3) crystals at the wavelengths of ∼4.4 and ∼4.8 m at a temperature of 78 K was achieved, respectively. The excitation of Fe ions in both samples by direct 2.94 m as well as ∼4.05 m radiation or indirectly via the Cr→ Fe ions’ energy transfer-based mechanism by 1.73 m radiation was demonstrated. Based on the obtained results, the possibility of developing novel coherent laser systems in mid-IR regions (∼2.3–2.5 and ∼4.4–4.9 m) based on AB matrices was presented.

Ultrabroadband Nanospectroscopy with a Laser-Driven Plasma Source

Scattering-type scanning near-field optical microscopy (s-SNOM) enables infrared spectroscopy at 10–20 nm spatial resolution through elastic light scattering. Coupled with an infrared light source, s-SNOM characterizes chemical compositions or probes nanoscale photonic phenomena on length scales 2 orders of magnitude below the diffraction limit. However, widespread use of s-SNOM as an analytical standard tool has been restrained to a large extent by the lack of a bright and affordable broadband light source. Here we present a turnkey thermal emitter based on a laser-driven plasma that offers incoherent radiation of a broader bandwidth (>1000 cm–1) and ∼40-fold higher brilliance than previous blackbody radiators in addition to a compact size and at a fraction of the cost of alternative coherent laser systems or synchrotrons. We demonstrate a nearly 1 order of magnitude increase in signal-to-noise in near-field spectra compared to existing incoherent emitters, which allows probing of not only inorganic mate...

Optical phase locking of two extended-cavity diode lasers with ultra-low phase noise for atom interferometry

We present a phase coherent laser system with ultra-low phase noise with a frequency difference of 6.9 GHz. The laser system consists of two extended-cavity diode lasers that are optically phase-locked with electrical feedback to the injection current of a slave laser. The bandwidth of the optical phase-locking loop is extended up to 8 MHz. We achieve the residual phase noise of two phase-locked lasers of below −120 dBrad2/Hz in the offset frequency range of 100 Hz–350 kHz and a flat phase noise of −127 dBrad2/Hz from 700 Hz to 20 kHz. These results are, to the best of our knowledge, the lowest phase noise level ever reported with two extended-cavity diode lasers.

Optical fiber-based laser remote sensor for airborne measurement of wind velocity and turbulence

We discuss an optical fiber-based continuous-wave coherent laser system for measuring the wind speed in undisturbed air ahead of an aircraft. The operational principles of the instrument are described, and estimates of performance are presented. The instrument is demonstrated as a single line of sight, and data from the inaugural test flight of August 2010 is presented. The system was successfully operated under various atmospheric conditions, including cloud and clear air up to 12 km (40,300 ft).

Remote sensing of atmospheric wind velocities using solid-state and CO/sub 2/ coherent laser systems

Coherent lidar/laser radar systems have been used for the remote measurement of atmospheric wind velocity since 1966. Both CW and pulsed coherent lidars have been developed and applied to a variety of ground-based and airborne applications. In recent years, most efforts have concentrated on pulsed CO/sub 2/ and solid-state Doppler lidars for the remote measurement of atmospheric wind velocities. Issues associated with the design and application of coherent lidars to atmospheric wind measurement are discussed. Coherent lidar/laser radar systems have been applied to detection and tracking of aircraft wake vortices, measurement of atmospheric wind fields during the space shuttle takeoff and landing, airborne windshear detection, ground-based airport microburst windshear monitoring, meteorological research, and environmental monitoring. Numerous examples of measurement results are presented. An assessment of the status of coherent lidar technology as practical devices for operational and research uses is addressed.

Remote detection of small vibrations of objects across the atmosphere with the aid of a CO2laser heterodyne system

A CO2 laser heterodyne transceiver was used in an experimental investigation of remote detection, across the real atmosphere, of small lf vibrations of the surface of an object located at a distance of 1.85 km. Estimates were obtained of the corresponding capabilities of a coherent laser system at distances up to 10 km and for different reflection characteristics of the objects. The results indicated that it should be possible to detect vibrations with amplitudes of the order of several nanometers at distances up to 2 km.