mW Of Continuous-wave Output Power Research Articles

High-Power Heterogeneously Integrated III-V/Silicon Superluminescent Diode

We demonstrate heterogeneously integrated O-band superluminescent diodes (SLDs) emitting 10 mW of continuous-wave output power at a device temperature of up to 65 °C. At 10 mW output power, the SLD has a wall-plug efficiency of 3.1% at 25 °C and 1.3% at 65 °C; a 3-dB optical bandwidth of 20-30 nm; and spectral modulation (ripple amplitude) of 0.13 (1.1 dB) at 25 °C and 0.09 (0.8 dB) at 65 °C. This is the highest reported output power and efficiency for a SLD integrated with silicon by more than one order of magnitude, which opens up new applications for cheaper and more compact SLD-based photonics integrated circuits.

Femtosecond laser written continuous-wave Nd3+:BaY2F8 waveguide laser at 1.3 μm

We experimentally demonstrate, for the first time to our knowledge, robust operation of a Nd3+:BaY2F8 waveguide laser at 1.3 μm without any parasitic lasing at any other wavelength. The best power performance was obtained with a depressed cladding waveguide, having a diameter of 70 μm, which was fabricated by employing femtosecond laser writing. The propagation loss of the waveguide was measured as 0.33 dB/cm at the wavelength of 761 nm. The power performance of the waveguide laser was investigated for E//z and E//y pumping polarizations by using butt-coupled flat resonator mirrors. Higher power performance was obtained for E//z pumping, where the resonator with the 6.2% transmitting output coupler produced 157 mW of continuous-wave output power at 1318 nm with 882 mW of pump power at 800 nm. The measured power slope efficiency was 19% with respect to the incident pump power. By using a different set of cavity optics, 1050-nm lasing performance was also studied, where E//z pumping at 800 nm with the 12% transmitting output coupler yielded 307 mW of output power with 31% slope efficiency. Use of a host medium with relatively low refractive index around 1.5 was instrumental in reducing the facet reflectivity and eliminating the possibility of parasitic lasing at 1.05 μm during 1.3-μm lasing.

Tunable continuous-wave laser operation of Tm3+ ion doped tellurite glass near 2 μm

We provide an experimental investigation of the absorption saturation and 1.9-μm lasing characteristics of a bulk Tm3+:TZLN glass with the host composition of 74TeO2–12ZnO–4La2O3–10Na2O. By using a z-scan saturation measurement, the absorption cross section at 794 nm was determined to be 5×10−21cm2, in reasonable agreement with the value of 6×10−21cm2 obtained from small-signal transmission measurement. In lasing experiments, double pumping was employed at 794 nm and the bulk Tm3+:TZLN glass laser operated at the free running wavelength of 1926 nm. As high as 15.4 mW of continuous-wave output power was obtained with a 2.15% transmitting output coupler at the absorbed pump power of 284 mW. The slope efficiency with respect to the absorbed pump power was 7.1%. By using the threshold and power efficiency data, the stimulated emission cross section was further determined to be 6.8×10−21cm2at 1926 nm. Finally, continuous tuning of the laser output was demonstrated between 1845 and 1973 nm by using a quartz birefringent plate.

Spectroscopic and laser properties of Er:LuGG crystal at ∼2.8 μm

We report ∼2.8 μm emission of Er3+-doped Lu3Ga5O12 crystal, as well as its laser performance. The continuous-wave (CW) and passively Q-switched lasers were both obtained for the first time at room temperature under 967 nm laser diode end pumping. A 384 mW of CW output power was obtained under the absorbed pump power of 3.28 W, corresponding to an optical-to-optical efficiency of 11.7%; the slope efficiency was 14.1%. A passively Q-switched laser with a maximum average output power of 274 mW was also achieved by utilizing a Bi2Te3/graphene heterostructure saturable absorber (SA). The shortest Q-switched pulse duration and the repetition rate were 340 ns and 135 kHz, respectively.

5-nJ Femtosecond Ti3+:sapphire laser pumped with a single 1 W green diode

We report a Kerr-lens mode-locked, extended-cavity femtosecond Ti3+:sapphire laser directly pumped at 520 nm with a 1 W AlInGaN green diode. To obtain energy scaling, the short x-cavity was extended with a q-preserving multi-pass cavity to reduce the pulse repetition rate to 5.78 MHz. With 880 mW of incident pump power, we obtained as high as 90 mW of continuous-wave output power from the short cavity by using a 3% output coupler. In the Kerr-lens mode-locked regime, the extended cavity produced nearly transform-limited 95 fs pulses at 776 nm. The resulting energy and peak power of the pulses were 5.1 nJ and 53 kW, respectively. To our knowledge, this represents the highest pulse energy directly obtained to date from a mode-locked, single-diode-pumped Ti3+:sapphire laser.

303 nm continuous wave ultraviolet laser generated by intracavity frequency-doubling of diode-pumped Pr3+:LiYF4 laser

We demonstrate an efficient and compact ultraviolet laser at 303 nm generated by intracavity frequency doubling of a continuous wave (CW) laser diode-pumped Pr3+:YLiF4 laser at 607 nm. A cesium lithium borate (CLBO) crystal, cut for critical type I phase matching at room temperature, is used for second-harmonic generation (SHG) of the fundamental laser. By using an InGaN laser diode array emitting at 444.3 nm with a maximum incident power of 10 W, as high as 68 mW of CW output power at 303 nm is achieved. The output power stability in 4 h is better than 2.85%. To the best of our knowledge, this is high efficient UV laser generated by frequency doubling of an InGaN laser diode array pumped Pr3+:YLiF4 laser.

Improved mid-infrared interband cascade light-emitting devices

We report interband cascade light-emitting devices (ICLEDs) emitting at peak wavelengths of 3.1 to 3.2 μm that display higher maximum output powers, radiances, and efficiencies than any earlier midwave-infrared LEDs when operated at 10 to 105°C. To enhance the output power, we split the ICLED’s 22 active stages into four groups positioned at antinodes of the optical field so that the emission interferes constructively when reflected at near-normal incidence from the metal contact of the epitaxial-side-down mounted device. At an applied bias of 9.6 V and injection current of 0.6 A, an ICLED with mesa diameter of 400 μm produces 3.1 mW of continuous-wave output power at T=10°C, which corresponds to a radiance of 0.79 W/cm2/sr. The same device generates 1.7 mW at T=105°C.

Narrow Ridge $\lambda \approx 3$ - $\mu \text{m}$ Cascade Diode Lasers With Output Power Above 100 mW at Room Temperature

Shallow narrow ridge two-stage cascade GaSb-based type-I quantum well diode lasers emitting at $\lambda \approx 3~\mu \text{m}$ were designed and fabricated. Efficient carrier recycling improved the device power conversion and slope efficiencies as compared with the standard multiple quantum well diode lasers. Devices generated more than 100 mW of continuous-wave output power in nearly diffraction limited beam at room temperature. Studies of the current dependence of the modal gain spectra confirmed increased tendency to lateral current spreading in cascade laser heterostructures as compared with the regular diode lasers.

Pr:YLF orange laser investigation at cryogenic temperature

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%.

All-solid-state 360 nm ultraviolet laser generated by intracavity frequency-doubling of diode-pumped Pr3+:YLiF4 laser

We demonstrate an efficient and compact ultraviolet laser at 360 nm generated by intracavity frequency doubling of a continuous wave (CW) laser diode-pumped Pr3+:YLiF4 laser at 721 nm. A lithium triborate crystal, cut for critical type I phase matching at room temperature, is used for second-harmonic generation of the fundamental laser. By using an InGaN laser diode emitting at 444.3 nm with a maximum incident power of 5 W, as high as 460 mW of CW output power at 360 nm is achieved. The optical-to-optical conversion efficiency is as high as 9.2%, and the output power stability in 4 h is better than 3.86%. To the best of our knowledge, this is high efficient UV laser generated by frequency doubling of an InGaN diode-pumped Pr3+:YLiF4 laser.

Diffraction limited 3.15 μm cascade diode lasers

Cascade GaSb-based type-I quantum well diode lasers emitting near 3.15 μm were designed and fabricated. The efficient carrier recycling between stages was confirmed by twofold increase of the efficiency of two-stage cascade laser as compared to reference single-stage devices. Narrow ridge cascade lasers generated more than 40 mW of continuous-wave output power in diffraction limited beam at room temperature.

Mid-infrared interband cascade light emitting devices with milliwatt output powers at room temperature

We demonstrate incoherent light emission peaked at λ = 3.3 μm from a 15-stage interband cascade active region. The interband cascade light emitting devices with mesa diameters ranging from 50 to 400 μm were mounted epitaxial-side-down, and light was extracted from the substrate side. At an applied bias of 8.7 V and injection current of 0.6 A, and without any measures taken to improve the poor out-coupling efficiency caused by total internal reflection, a 400-μm-diameter device produced 1.6 mW of continuous-wave output power at T = 25 °C. Mesas with smaller diameters displayed emission intensities as high as 1.7 W/cm2.

All-solid-state low noise Yb:YAG/LBO green laser at 515 nm

We report the efficient compact green laser at 515 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode-pumped Yb:YAG laser on the transition at 1030 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. With the incident pump power of 10 W, 270 mW of CW output power at 515 nm is achieved with 15-mm-long LBO. The optical-to-optical conversion efficiency is 2.7%, and the power stability in 8 h is better than 2.36% with low noise. 2013 Pleiades Publishing, Ltd.

Room temperature operated diffraction limited λ ≃ 3 µm diode lasers with 37 mW of continuous‐wave output power

Single spatial mode GaSb-based type-I quantum well diode lasers operating near 3 μm at room temperature were designed and fabricated by chlorine-free dry etching technique. The etching profile was optimised to minimise the optical loss. The 5.5 μm-wide ridge lasers demonstrated the same slope efficiency as that of 100 μm-wide multimode devices and generated 37 mW of continuous-wave output power at 17°C.

Narrow linewidth Yb-doped fiber laser at 1120 nm

A 974 nm laser diode pumped 1120 nm ytterbium (Yb)-doped fiber laser with all fiber components has been experimentally demonstrated. The resonator is composed of a normal single-mode Yb-doped fiber 1 m long and a pair of fiber Bragg gratings. Up to 21.6 mW of continuous-wave output power is generated when the launched pump power is 161 mW with an optical-to-optical conversion efficiency of 13.4%. The central wavelength is 1120.89 nm with a linewidth as narrow as 0.02 nm. Additionally, a similar fiber laser with a 2 m long gain medium displays a broadened linewidth. The results of the two fiber lasers are compared and discussed in the paper.

All-solid-state CW Nd:GdVO4-LBO red laser under direct 912 nm pumping

We report a red laser at 670.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1341 nm Nd:GdVO4 laser under in-band diode pumping at 912 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 8.9 W, as high as 347 mW of CW output power at 670.5 nm is achieved. The fluctuation of the red output power was better than 3.7% in the given 30 min, and the beam quality factor M 2 is 1.65.

Continuous wave Nd:YAG-BiBO blue laser under direct 869 nm pumping

We report a blue laser at 473 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 946 nm Nd:YAG laser under in-band diode pumping at 869 nm. An BiBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 8.6 W, as high as 721 mW of CW output power at 473 nm is achieved. The optical-to-optical conversion efficiency is up to 8.4%, and the fluctuation of the blue output power was better than 3.5% in the given 30 min.

Diode-pumped Yb:GSO-LBO laser at 544 nm

We report a green laser at 544 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1088 nm Yb:GSO laser under in-band diode pumping at 940 nm. An LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 17.8 W, as high as 444 mW of CW output power at 544 nm is achieved. The fluctuation of the green output power was better than 4.6% in the given 4 h.

Diode-pumped Yb:Y2SiO5-LiB3O5 cyan laser at 501.7 nm

Efficient continuous-wave intracavity frequency doubling of a diode-end-pumped Yb:Y2SiO5 laser operating at 1003.4 nm has been demonstrated for the first time. With 18.3 W of diode pump power and the frequency-doubling crystal LiB3O5 (LBO), as high as 239 mW of continuous-wave output power at 501.7 nm is achieved. The output power stability over 30 min is better than 2.8%. The laser beam quality M2 factors are 1.85 and 2.13 in both horizontal and vertical dimensions, respectively.

High-power, broadly tunable, and low-quantum-defect KGd_1-xLu_x(WO_4)_2:Yb^3+ channel waveguide lasers

In KGd(1-x)Lu(x)(WO(4))(2):Yb(3+) channel waveguides grown onto KY(WO(4))(2) substrates by liquid phase epitaxy and microstructured by Ar+ beam etching, we produced 418 mW of continuous-wave output power at 1023 nm with a slope efficiency of 71% and a threshold of 40 mW of launched pump power at 981 nm. The degree of output coupling was 70%. By grating tuning in an extended cavity and pumping at 930 nm, we demonstrated laser operation from 980 nm to 1045 nm. When pumping at 973 nm, lasing at 980 nm with a record-low quantum defect of 0.7% was achieved.