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We proposed a compact experimental scheme for a low repetition rate, high-energy, nanosecond laser at 604 nm based on Pr: YLF crystal at room temperature. The thermal effect of Pr: YLF crystal was simulated, which demonstrated that high energy 604 nm laser line at room temperature can be generated with appropriate parameters such as crystal and the laser output coupling. Then a stable 604 nm orange laser pumped by a pulsed 444 nm optical parametric oscillator was developed experimentally. A high pulse energy of 63 μJ with 30 ns pulse duration at a repetition rate of 10 Hz was obtained. To the best of our knowledge, this is the first report of such a high-energy 604 nm laser using a gain switched pump source at room temperature.

The crystal growth, polarized spectral properties, Judd-Ofelt (JO) analysis and lifetime of Sm:CaGdAlO4 (Sm:CGA) crystal were reported for the first time. Sm:CGA crystal with size of Φ4 × 33 mm3 was grown by the floating zone (FZ) method. The peak absorption cross-sections at 407 nm were calculated to be 3.41 × 10−20cm2 and 3.20 × 10−20cm2 for the σ and π polarization, and the largest stimulated emission cross-sections at 601 nm were 5.10 × 10−21cm2 and 4.66 × 10−21cm2, respectively. The absorption and emission cross-sections were several times larger than that of Sm:LiYF4. The JO intensity parameters of Ω2, Ω4 and Ω6 were calculated to be 3.0 × 10−20cm2, 6.1 × 10−20cm2 and 6.5 × 10−20cm2, respectively. The lifetime of the 4G5/2 level was obtained to be 0.69 ms. All the results indicate that Sm:CGA crystal is a potential laser host for the reddish-orange laser operation.

Sm:YAlO3 (Sm:YAP) crystal with size of Φ28 × 80 mm3 was grown by Czochralski (Cz) method. Polarized absorption spectra and fluorescence spectra of Sm:YAP crystal were discussed for the first time. The peak emission cross-sections were calculated to be 0.80 × 10−21 cm2 (604 nm for a-polarization), 1.82 × 10−21 cm2 (604 nm for b-polarization) and 1.63 × 10−21 cm2 (610 nm for c-polarization), respectively. The Judd-Ofelt (JO) intensity parameters were calculated to be Ω 2 = 2.59 × 10−20 cm2, Ω 4 = 1.78 × 10−20 cm2 and Ω 6 = 2.98 × 10−20 cm2, respectively. The decay lifetime of 4G5/2 energy level was measured to be 2.51 ms. All above results indicate the Sm:YAP crystal may be a potential candidate of reddish-orange laser pumped directly by the GaN/InGaN laser diode.

We report an all-solid-state tunable CW orange laser based on single-pass sum-frequency generation in step-chirped PPMgO: LN crystal. Two laser sources, a tunable laser (1550 nm) and an ASE laser (1525–1650 nm) are used interchangeably as pumps and mixed with a fixed 975 nm signal laser. Up to 4.3 mW at 597 nm is generated corresponding to 0.87% nonlinear conversion efficiency and the beam quality (M2) value of about 2.5 is measured. The output wavelength can be tuned up to ~ 5.66 nm by varying the position of focusing inside the crystal and by temperature, which makes possible the practical application of our device for wavelength selection and diversity in the orange spectral range.

Sm 3+ -doped La 2 CaB 10 O 19 (Sm:LCB) crystal with size of 40×25×15 mm 3 has been grown by the top-seeded solution growth (TSSG) method. The absorption and fluorescence spectra of Sm:LCB were measured at room temperature, and the fundamental spectral parameters, including transition probability A , fluorescence branch ratio β c , radioactive lifetime τ r , emission cross-sections σ em and intensity parameters Ω t (2,4,6) , have been calculated by applying the Judd–Ofelt theory. In Sm:LCB crystal, a strong 599 nm orange fluorescence emitting peak was observed under 410 nm excitation, which may be applied in the medicine and biological detection. Sm:LCB crystal may be a promising orange laser material.

A Watt-level broadband orange laser is demonstrated by use of double-pass sum frequency mixing in a step-chirped MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal (Λ = 10.1–10.4 µm). The temperature-gradient technique is used to enhance the bandwidth of the output spectrum. The maximum output of the orange laser in the 600 nm spectral region is up to 1.1 W whereas the maximum bandwidth of ~7.2 nm was accomplished employing a 40 mm long MgO:PPLN structure. This scheme presents an attractive approach for the generation of high power and broadband short-wavelength lasers from a single crystal, which may extend the potential biomedical and spectroscopic applications.

The fabrication of orange-emitting semiconductor laser on interdiffused InGaP/InAlGaP structure is reported. The lasers lased at 22°C at a wavelength as short as 608 nm with threshold current density of 3.4 KAcm−2 and a maximum output power of ∼46 mW. This is the shortest wavelength electrically pumped semiconductor laser emission from the InGaP/InAlGaP structure.

We report continuous-wave orange laser operation at 607.5 nm of a 8 mm long 0.2at% Pr:LiYF 4 single crystal with an improved laser slope efficiency. Using a single InGaN laser diode emitting at ∼444 nm as a pump source, an output power of ∼200 mW was achieved with a threshold absorbed pump power of ∼150 mW and a laser slope efficiency of nearly 42%. M 2 factors of 1.40 and 1.28 were measured in the x and y directions, respectively, attesting to the good quality of the output laser beam.

We report for the first time a continuous-wave (CW) orange radiation at 598 nm by intracavity sum-frequency generation of 1341 nm Nd:GdVO4 laser and 1080 nm Nd:YAlO3 (Nd:YAP) laser. Orange laser is obtained by using a doubly cavity, type-II critical phase matching KTP crystal sum-frequency mixing. With total pump power of 36 W, TEM00 mode orange laser at 598 nm of 268 mW is obtained. The orange power stability in 30 min is better than 3.8%.

We report for the first time a continuous wave (CW) coherent radiation at 611 nm by intracavity sum-frequency generation of 1064 nm Nd:YVO4 laser and 1433 nm Nd:YAP laser. Red-orange laser is obtained by using a doubly cavity, type-II critical phase matching KTP crystal sum-frequency mixing. With total pump power of 27.9 W (17.8 W pump power for 1433 nm Nd:YAP laser and 10.1 W pump power for 1064 nm Nd:YVO4 laser), TEM00 mode red-orange laser at 611 nm of 1.15 W is obtained. The red-orange power stability in 30 min is better than 4.3%.

Medical lasers used as ophthalmic photocoagulator are briefly reviewed. The author describes some new approaches to develop a novel laser source for these applications, and then discusses future trends and some options for medical applications. At present, the domestic market of laser equipment for medical applications is smaller than that for industrial applications, which has restricted constant growth. In this paper, laser sources for photocoagulation are mainly discussed. Photocoagulators are influenced by the development of laser sources. New applications at extremely high bright orange fiber laser photocoagulators are expected from the perspective of life cycle of new products.

We report on the first demonstration of InGaP/InAlGaP based orange semiconductor laser (OSL) and yellow superluminescent diode (YSLD) emitting at a wavelength of 608nm and 583nm respectively. The total output power of YSLD is ∼4.5mW which is the highest ever reported power on this material system at room-temperature.

Detailed absorption and time-resolved emission data resulting from selective laser excitation are presented. True CW laser operation at red and orange laser wavelengths are reported.

The temperature influence on the lasing properties of Pr:YLF crystal at orange laser transition is reported. The output characteristics were investigated at different active medium temperatures within the range of 80–300 K. Using a 1-W InGaN pump laser-diode, 350 mW of continuous-wave output power at 604 nm wavelength at 80 K crystal temperature is demonstrated. The corresponding slope efficiency related to the absorbed pump power was 46%.

In 1972 Ente Nazionale Idrocarburi sponsored a program to holographically record the images of Venetian sculptural treasures for archival purposes. At Laboratorio San Gregorio, where the initial holography took place, G. Musumeci and K. Hempel suggested an experiment to determine whether the concentrated beam from the ruby holographic laser could ablate black-patina crusts from decaying marble. Initial success of a laser-divestment test on a Palazzo Ducale capital launched a search for funding to enable a full-scale laser-conservation demonstration. Later, at a Caltech reunion one of the author's physics professors (Carl Anderson, the discoverer of mu mesons and the positron), noting the prominence of the Venice Film Festival suggested our approaching the motion picture industry. Many years earlier Anderson's Caltech classmate, Frank Capra, had supported the research that led to the discovery of cosmic-ray-generated antimatter on Pikes Peak. (After Caltech, Capra had become a director at Columbia Studios.) Anderson's chance comment led to an introduction to producer Jack Warner at a festival screening of his "A Clockwork Orange" in Asolo. He and his friends contributed US$5000 toward the laser conservation of a marble relief of "The Last Supper" in the Porta della Carta of Venice. This work was conducted in 1980 under the direction of Arch. G. Calcagno. In 1981 it was found that the granite veneer or the newly completed Warner Center Tower had been stained during transit from the quarry. The Venice laser successfully restored the veneer, thereby returning the Warner Brothers' favor.

Reflectance physicalism only provides a partial picture of the ontology of color. Byrne & Hilbert’ account is unsatisfactory because the replacement of reflectance functions by productance functions is ad hoc, unclear, and only leads to new problems. Furthermore, the effects of color contrast and differences in illumination are not really taken seriously: Too many “real” colors are tacitly dismissed as illusory, and this for arbitrary reasons. We claim that there cannot be an all-embracing ontology for color.

Bleaching experiments were carried out at room temperature on rhodopsin in isolated rat, frog and ray retinas with blue and orange laser flashes of very high energy and duration less than 3 μsec. Blue flashes bleached a maximum of about 50% at the highest energies; orange ones bleached about 30% at intermediate energies but the value decreased to below 20% as the energy increased. This bleaching behaviour can be explained in terms of a kinetic model which assumes that bleaching is photoreversed during the flashes and which incorporates the relevant properties of rhodopsin, isorhodopsin, bathorhodopsin and lumirhodopsin.

In1−xGaxP laser diodes which emit coherently at 80 °K at wavelengths as short as 6105 A with threshold current densities of 4000–6000 A/cm2 have been fabricated from vapor‐grown In1−xGaxP p‐n junction structures. This is the shortest‐wavelength laser emission and the first example of coherent orange emission yet reported from a semiconductor p‐n junction. From vapor‐grown In1−xGaxP spontaneous‐light‐emitting diodes, external quantum efficiencies in excess of 0.1% have been obtained for orange and red emission at room temperature.