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We describe a ‘clock control unit’ based on a dual-axis cubic cavity (DACC) for the frequency stabilisation of lasers involved in a strontium optical lattice clock. The DACC, which ultimately targets deployment in space applications, provides a short-term stable reference for all auxiliary lasers—i.e. cooling, clear-out, and optical lattice—in a single multi-band cavity. Long-term cavity drift is compensated by a feed-forward scheme exploiting a fixed physical relation to an orthogonal second cavity axis; either by reference to an ultrastable 698 nm clock laser, or by exploiting the differential drift between orthogonal axes extracted by a single laser in common view. Via a change of mirror set in the cavity axis accessed by the clock laser, the system could also provide stabilisation for sub-Hz linewidths at the 698 nm clock wavelength, fulfilling all stabilisation requirements of the clock.

In this work, comparative study of CW multi-wavelength Nd:YVO 4 , Nd:YAG and Nd:GYSGG lasers at round 1.3 μm is demonstrated experimentally. Under the same cavity structure and an equal pump power, the Nd:YVO 4 laser can generate the maximum output power due its admirable stimulated emission cross-section, but it emits only single-wavelength line at 1342 nm. The Nd:YAG laser can radiate dual-wavelength lines at 1319 and 1338 nm. While the Nd:GYSGG laser can have got three distinct lines at around 1.3 μm with the lowest output power.

Outdoor field scans with MWLP and BoniRob for spectral+3D data of plants.Pixel-based classification, human interaction with very little effort for labeling.Classifier with spectral and 3D surface features, practicable model adaptation. State-of-the-art object-based approaches to automatic plant classification for crop/weed discrimination are reported to work with typical classification rates of 8090% under laboratory or restricted field conditions. Adapting their parameter sets and classifiers to match changing field situation is laborious, yet it is required for practical application. Pixel-based classification allows adjusting the classifier model in the field easily by adding a few marks to sample data; however, pixel-based classification of camera data for crop/weed discrimination is impractical, as pixel features lack descriptiveness. This paper contributes a multi-wavelength laser line profile (MWLP) system for scanning the plants and obtaining sensor data, yielding image-based 3D range data, matched spectral reflectance, and scattering data at multiple wavelengths for each pixel. Using these descriptive pixel features, pixel-based Bayesian classification for crop/weed discrimination requires very few field-specific label data, thus allowing In-Field-Labeling for classifier adaptation to specific field situations. For different field situations and two different crops (carrots (Daucus carota) and corn salad (Valerianella locusta)) the classification using spectral and 3D features applying classifiers generated from very few marks in sample data (i.e., with very little effort for labeling), was successfully demonstrated, thereby achieving misclassification rates comparable to the best literature values.

We proposed a wavelength-grid free WDM system, which allows wavelength drift so that use of uncooled laser and high-density WDM is enabled. A multi-wavelength QD-LD for the system was also demonstrated.

Spider nevi (SN) are one of common vascular diseases. Different treatment techniques have been described for SN previously, including electrocoagulation, argon laser, pulsed dye lasers (PDL), pulsed potassium titanylphosphate laser (KTP), and 1064-nm neodymium yttrium-aluminum-garnet (Nd:YAG) laser. These methods are effective but may require good technical management, multiple treatments, and often result in scarring or pigmentation. Multi-wavelength laser combined with 595-nm PDL followed by 1064-nm Nd:YAG and can be selectively absorbed by hemoglobin in vessels. The 595-nm laser can target shallow vessels whereas the 1064-nm laser may target deeper vessels due to the different penetration capacities of these wavelengths. Moreover, Nd:YAG absorption is remarkable increased following by PDL treatment. Multi-wavelength laser treatments have been successfully used for vascular diseases but there is little experience in SN therapy. Consequently, these treatment parameters have not been established for SN, particularly in Asian patients with Fitzpatrick skin type (FST) IV. Report experience with using multi-wavelength laser for SN treatment in Asian patients with FST IV. Forty-three SN lesions received multi-wavelength laser treatments via a PDL followed by an Nd:YAG laser. The treatment was performed at 7 mm spot size at 9.5–11 J/cm2, 10 ms with PDL, followed by Nd:YAG at 40–50 J/cm2, 15 ms. The laser treatments were performed with a single pass without overlap. Complete resolution was observed in 40 lesions and an 80–90% improvement in the other three lesions after one treatment session. One patient had superficial scarring. Four patients had hyperpigmentation that resolved within 3 months. Multi-wavelength laser treatments are fast and effective interventions for SN treatment in Asian patients with minimal adverse effects when appropriate parameters are set.

We are developing a multi-wavelength laser for the two-step laser time-of-flight mass-spectrometer (L2MS). The L2MS is designed to detect hydrocarbons in organically-doped analog minerals, including cryogenic Ocean World-relevant ices and mixtures for future astrobiology missions.

A simplified multi-wavelength laser speckle contrast imaging system by using a single holographic optical element is proposed. By using the optical properties of holographic optical element (HOE), which has transparency and angular selectivity, the HOE can replace many optical elements. The HOE functions as an integrated optical element: multi-wavelength beam guiding optics. To record the HOE, recording wavelength precompensation method is used for providing flexibility for recording setup. By adopting the precompensation method, volume gratings to be utilized by various wavelengths can be recorded by a single wavelength laser system. For using multiple wavelength with a single HOE, wavelength-multiplexing is conducted by controlling exposure durations on medium. To verify the feasibility of proposed method, the diffraction efficiency of HOE is measured.

To obtain 1064 nm/532 nm/660 nm three wavelength lasers operating simultaneously or singly, a novel LD side-pumped Nd 3+ :YAG laser system with acousto-optic Q-switched and nonlinear frequency conversion technologies was investigated. When the three wavelength lasers output singly and the Pumping power was 103 W, 1064 nm laser was 14.5 W and the green and red lasers reached 4.7 W and 1.6 W, respectively, at the repetition rate of 10.5 kHz and 11.5 kHz. When they worked simultaneously, the red, green and infrared lasers were obtained with the output power distribution of 1.0 W at 660 nm, 4.3 W at 532 nm and 10.1 W at 1064 nm, and the instability was less than 2% within 3 h.

For the microwave photonic filters constructed with two cascaded Hi-Bi fibers, we demonstrate theoretically and experimentally a new technique that uses a dual- or tri-wavelength spacing-tunable laser source to greatly suppress the sensitivity of the filter response to environmental perturbations without the introduction of the phase-induced intensity noise. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 207–212, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24844

A cruciform cavity is presented for multi-wavelength laser generation. On the basis of considering the optimal power ratio and good spatial overlap of the two fundamental beams, the maximum output power of 589 nm laser reaches 3.5 W when the pumping power of Nd:YAG A and Nd:YAG B are 311.5 W and 261.8 W, respectively. At the same time, the other wavelength lasers are also obtained with the output power distribution of 2.5 W at 660nm, 15W at 532nm, 100m W at 1319nm and 240mW at 1064nm. The corresponding beam quality factors are Mx2 = 4.93, My2 = 5.01 at 589 nm, Mx2 = 4.51, My2 = 4.85 at 660 nm, and Mx2 = 4.12, My2 = 3.96 at 532nm, respectively. The instabilities of the three visible lights are measured, which are also less than 2% within three hours.

We have demonstrated an over 40-channel multi-wavelength laser comb source with the 50-GHz equal frequency spacing between the adjacent channels over the C-band wavelength range. The output spectra could be described by using the simplified stimulated four-wave nonlinear coupled equations taking into account the third-order nonlinear optical interaction in the single-mode dispersion-shifted fibers. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 92–94, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22993

A novel multi-wavelength laser monolithically integrated on InP is presented. The device consists of four channels of Fabry-Perot lasers using two-port multimode interference reflectors (MIRs) and a single mode operation for each channel is realized by the filtered-feedback from arrayed waveguide grating(AWG).

Receiving system for the laser equipment performance testing, although the use of laser simulation testing equipment can overcome the high cost of traditional methods equipment, strict environmental requirements on the venue and other issues. But in the practical application of various laser devices under test, wavelength and frequency are varies. So that laser simulation testing equipment requires a higher degree of comprehensive and intelligence. Therefore, we propose a new comprehensive multi-wavelength laser simulated-testing technology, and study the design and application of comprehensive laser simulated-testing instrument in the test of receiving system of laser equipment. Our design process in these devices there are two technical bottlenecks for us and we propose efficient solutions:(1)Complex structure of the optical system, the volume mass is too large; (2)Different wavelength laser firing unit with low degree of integration and the high cost of processing. The instrument has the advantage, the ability to easily and real-time test different wavelengths and frequency of laser devices to receiving system with a high degree of device comprehensive and low cost.

We present an arrayed waveguide grating multi-wavelength laser (MWL). The device is operated with five wavelength channels of 194 GHz spacing around a central wavelength of 1.57 μm. A side mode suppression ratio of better than 35 dB for all channels is demonstrated. A very attractive feature of the MWL is that it has been realized by a novel one step regrowth approach to achieve a high quality active and passive interface.

JMDT is a Navy/Marine Corps 6.2 Exploratory Development program that is closely coordinated with the 6.4 COBRA acquisition program. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. Prior to transition to acquisition, the COBRA ATD was extremely successful in demonstrating a passive airborne multispectral video sensor system operating in the tactical Pioneer unmanned aerial vehicle (UAV), combined with an integrated ground station subsystem to detect and locate minefields from surf zone to inland areas. JMDT is investigating advanced technology solutions for future enhancements in mine field detection capability beyond the current COBRA ATD demonstrated capabilities. JMDT has recently been delivered next- generation, innovative hardware which was specified by the Coastal System Station and developed under contract. This hardware includes an agile-tuning multispectral, polarimetric, digital video camera and advanced multi wavelength laser illumination technologies to extend the same sorts of multispectral detections from a UAV into the night and over shallow water and other difficult littoral regions. One of these illumination devices is an ultra- compact, highly-efficient near-IR laser diode array. The other is a multi-wavelength range-gateable laser. Additionally, in conjunction with this new technology, algorithm enhancements are being developed in JMDT for future naval capabilities which will outperform the already impressive record of automatic detection of minefields demonstrated by the COBAR ATD.

An efficient laser operation of disordered Nd:LiGd(WO4)2 laser crystal, end-pumped by a quasi-CW 808 nm diode laser, has been demonstrated in both free-running and actively Q-switched modes. Multi-wavelength emission around 1.06 μm was obtained simultaneously in this paper. In free-running status, 0.63 W laser output was obtained, giving a slope efficiency of 40.6%. When the repetition rate was 40 kHz in Q-switched operation, a maximum average output power of 0.43 W and a slope efficiency of 30.2% were obtained. This work indicated that Nd:LiGd(WO4)2 could be a promising laser crystal for THz, mode-locked and tunable laser applications.

Novel multi-wavelength laser, based on semiconductor optical amplifier (SOA) and cascaded two-stage sampled fibre gratings, is theoretically and experimentally investigated in this paper. The reflection spectrum of the sampled fibre grating and lasing output spectrum are calculated. Exploiting SOA and sampled fibre grating manufactured by our laboratory,a multi-wavelength laser with 11 wavelengths, in which the output power difference is smaller than 1dB, is achieved. Compared with the scheme based on the ordinary sampled fibre grating, more lasing wavelengths and more uniform lasing output power can be achieved in the novel scheme, which can be concluded from both theoretical calculation and experimental analysis.

The authors have been involved for a number of years with the design and production of a range of aspheric doublet lenses for use as focusing elements in high-power multi-wavelength laser systems. This paper gives a brief resume of the design and manufacture of such lenses but concentrates on recent improvements in techniques and the final testing and performance. They also describe the performance of a multi-wavelength singlet aspheric lens. The quasi-far-field performance of the lens, and its correction by the removal of surface imperfections, is described and compared with an assessment of the lens based on its focal properties.