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Semiconductor disk lasers (SDLs), also known as optically pumped vertical external-cavity surface-emitting lasers (VECSELs), offer unparalleled features combining high beam quality, large wavelength coverage, multi-watt output power, narrow linewidth, and broad tuning range. Moreover, relative to the features they provide, SDLs are compact and cost-effective systems. Their unique properties have already been recognized in biophotonics, for example, in photocoagulation treatment of macular degeneration using yellow radiation and multiphoton imaging, yet their full spread to applications is still to come. This chapter provides an overview of key technology concepts related to SDLs and a summary of the most important developments in terms of wavelength coverage and output powers. Specific developments are presented for SDLs emitting continuous wave (CW) radiation at the yellow-orange-red optical spectrum and for SDLs emitting picosecond pulses at red wavelengths. The chapter is concluded with a review of several biophotonics applications and their needs for laser sources, which are then put in a perspective of current SDL achievements.

The first monolithic GaAs-based vertical-external-cavity surface-emitting laser (VECSEL) operating at 1550 nm is reported. The VECSEL operation is based on a gain mirror which was grown in a single growth run by plasma-assisted molecular beam epitaxy. The gain mirror comprised eight GaInNAsSb/GaAs quantum wells with a photoluminescence peak at 1505 nm and an AlAs/GaAs distributed Bragg reflector ensuring high reflectivity. The VECSEL chip was pumped with an 808-nm diode laser that had a large quantum defect in respect to the lasing wavelength. An output power of 80 mW in continuous wave mode and 210 mW in pulsed pump mode are demonstrated close to room temperature.

We report on a frequency-doubled VECSEL emitting at 512.6 nm. The laser spectrum was narrowed with a Volume Bragg Grating and the intracavity frequency-doubling was achieved with a periodically poled MgO-doped lithium niobate.

We report on a frequency doubled vertical-external-cavity surface-emitting laser emitting 5.6 W at 635 nm. The cavity employed a wafer-fused AlInGaAs/InP-AlAs/GaAs gain mirror in a V-shaped configuration. The heatsink temperature was 20 °C.

We demonstrate a semiconductor disk laser emitting at 1275nm, employing a wafer fused AlInGaAs/InP-AlAs/GaAs gain mirror. A built-in Au-reflector was used to reflect the pump light not absorbed in a single pass through the gain chip active region. The laser exhibited an output power of 33 W for a pump spot with a diameter of 0.86 mm, an output coupler of 2.5%, and a heat-sink temperature of -5°C. When the temperature of the heat-sink was increased to 15°C, the maximum output power reached a value of ∼24 W. The study reveals that the wafer fused gain mirrors have a high optical quality and good uniformity enabling scaling of the maximum emitted power with the diameter of the pump spot, i.e. at least up to the 1 mm diameter. publishedVersion

Optically pumped semiconductor lasers in conjunction with intra-cavity frequency conversion and tuning elements offer high continuous-wave power, narrow linewidth, and broad tunability. As a result, they are well suited to precision spectroscopic applications. We describe the development and testing of optically pumped semiconductor lasers operating at fundamental wavelengths of 1119 and 1178 nm. The fourth and second harmonic wavelengths are resonant with transitions in Mg II and Na I, respectively. We demonstrate continuously tunable, single-frequency lasers with watt-level average power at 1119, 1178, and 589 nm.

We demonstrate an OP-VECSEL prototype emitting more than 6W of CW output power at 625 nm. We employ dilute nitride (GaInNAs) quantum wells emitting fundamentally at 1250 nm together with intracavity frequency doubling. submittedVersion

We report the development of an intracavity-frequency-doubled vertical external-cavity surface-emitting laser (VECSEL) emitting at 571 nm for photoionization of magnesium. The laser employs a V-cavity geometry with a gain chip at the end of one cavity arm and a lithium triborate (LBO) crystal for second harmonic generation. The gain chip has a bottom-emitting design with ten GaInAs quantum wells of 7 nm thickness, which are strain compensated by GaAsP. The system is capable of producing up to 2.4 ± 0.1 W (total power in two separate output beams) in the visible. The free-running relative intensity noise was measured to be below −55 dBc/Hz over all frequencies from 1 Hz to 1 MHz. With acoustic isolation and temperature regulation of the laser breadboard, the mode-hop free operation time is typically over 5 hrs. To improve the long-term frequency stability, the laser can be locked to a Doppler-free transition of molecular iodine. To estimate the short-term linewidth, the laser was tuned to the resonance of a reference cavity. From analysis of the on-resonance Hansch-Couillaud error signal we infer a linewidth of 50 ± 10 kHz. Light at 285 nm is generated with an external build-up cavity containing a β-barium borate (BBO) crystal. The UV light is used for loading 25Mg+ ions in a surface-electrode RF Paul trap. These results demonstrate the applicability and versatility of high-power, single-frequency VECSELs with intracavity harmonic generation for applications in atomic and molecular physics.

We report intracavity Raman conversion of a long-wavelength InGaAs-QW VECSEL to ~1320 nm, the longest wavelength yet achieved by a VECSEL-pumped Raman laser. The setup consisted of a VECSEL capable of emitting >17W at 1180nm and tunable from 1141-1203nm and a 30-mm-long KGd(WO4)2 (KGW) Raman crystal in a coupled-cavity Raman resonator. The Raman cavity was separated from the VECSEL resonator by a tilted dichroic mirror, which steers the Raman beam to an output coupler external to the VECSEL. The spectral emission of the VECSEL, and consequently of the Raman laser, was set by a 4-mm-thick quartz birefringent filter in the VECSEL cavity. The KGW Raman laser was capable of emitting 2.5W at 1315 nm, with M2~2.7 and >4% diode-to-Stokes conversion efficiency. The Raman laser emission was tunable from 1295-1340 nm, limited by the free spectral range of the birefringent filter. Spectral broadening of the fundamental emission was observed during Raman conversion. At the maximum Raman laser output power, the total linewidth of the VECSEL spectrum was ~0:7nm FWHM. As a consequence, the Raman laser emission was also relatively broad (~0.9nm FWHM). Narrow (

We review the recent advances in the development of semiconductor disk lasers (SDLs) producing yellow-orange and mid-IR radiation. In particular, we focus on presenting the fabrication challenges and characteristics of high-power GaInNAs- and GaSb-based gain mirrors. These two material systems have recently sparked a new wave of interest in developing SDLs for high-impact applications in medicine, spectroscopy, or astronomy. The dilute nitride (GaInNAs) gain mirrors enable emission of more than 11 W of output power at a wavelength range of 1180–1200 nm and subsequent intracavity frequency doubling to generate yellow-orange radiation with power exceeding 7 W. The GaSb gain mirrors have been used to leverage the advantages offered by SDLs to the 2–3 μm wavelength range. Most recently, GaSb-based SDLs incorporating semiconductor saturable absorber mirrors were used to generate optical pulses as short as 384 fs at 2 μm, the shortest pulses obtained from a semiconductor laser at this wavelength range.

Pulses of 118 nJ at the repetition rate of 170 kHz and central wavelength of 2097 nm have been produced by holmium fiber laser Q-switched by carbon nanotube saturable absorber. Efficient operation of holmium fiber with fairly high-doping level has been demonstrated by using refined preform fabrication, which allowed for short-length cavity laser. The results demonstrate the practical potential of holmium fibers for Q-switched lasers with high-repetition rate operating above 2 μm wavelength.

We demonstrate dual-wavelength emission from optically pumped vertical-external-cavity surface-emitting lasers (VECSELs) with two different gain mirror designs. The first gain mirror design (S1) generated an optical output power of 0.39 W at λS = 984 nm and 0.30 W at λL = 1042 nm. A VECSEL using the second gain mirror design (S2) generated a maximum optical output power of 0.75 W at λS = 966 nm and 1.38 W at λL = 1047 nm. VESCELs using either gain mirror design exhibited self-pulsating behaviour in the high output power regime. In the VECSEL using the S1 gain mirror design, selfpulsation started beyond the λS output power of 140 mW and λL output power of 115 mW. The corresponding output power limits in the VECSEL using the S2 gain mirror were 300 mW for both wavelengths. Keywords: vertical external-cavity surface-emitting lasers, resonant periodic gain structure, semiconductor lasers

We show how to use a modified poly-dimethyl-siloxane (PDMS) soft stamp to reduce pattern deformation and residual layer thickness in soft UV-nanoimprint lithography. A soft stamp thinned with toluene reduces the residual layer of a resist by as much as 50% compared to an unthinned stamp. We apply the soft UV-nanoimprint to prepare nanopatterned waveguides for a single-frequency diode laser. This laser operates with a side-mode suppression ratio of 50dB, which indicates that the patterns are precise and uniform over the whole imprint field. To the best of our knowledge, this is the first single-frequency laser fabricated by soft UV-nanoimprint technology.

The paper presents simulation results for laterally-corrugated ridge-waveguide distributed-feedback (DFB) semiconductor lasers emitting at 980 nm, along with measured results. The effect of the corrugation on the laser output characteristics is discussed. Almost 50 dB side-mode suppression ratio was achieved for the laterally-corrugated ridge waveguide DFB lasers fabricated using nano-imprint-lithography.

A nonlinear-optical conversion process in a dual-wavelength vertical-external-cavity surface-emitting laser that leads to the generation of difference-frequency radiation in the long-wavelength part of the mid-infrared range (∼17.7 μm) is analyzed numerically. The nonlinear crystal of GaAs is incorporated in the output-coupler mirror and, at the same time, is placed in a Fabry-Perot cavity tuned to the difference frequency. It is shown that the dependence of the nonlinear-conversion efficiency on the GaAs crystal thickness exhibits a pronounced resonance behavior and that the peak power of the radiation in the mid-infrared range can be as high as a few milliwatts with the parameters of the laser and the optical pump readily attainable experimentally.

Experiments in atomic, molecular, and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power, and intensity stability. Vertical external-cavity surface-emitting lasers (VECSELs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. Here we present and characterize VECSEL systems that can perform all laser-based tasks for quantum information processing experiments with trapped magnesium ions. For photoionization of neutral magnesium, 570.6$\,$nm light is generated with an intracavity frequency-doubled VECSEL containing a lithium triborate (LBO) crystal for second harmonic generation. External frequency doubling produces 285.3$\,$nm light for resonant interaction with the $^{1}S_{0}\leftrightarrow$ $^{1}P_{1}$ transition of neutral Mg. Using an externally frequency-quadrupled VECSEL, we implement Doppler cooling of $^{25}$Mg$^{+}$ on the 279.6$\,$nm $^{2}S_{1/2}\leftrightarrow$ $^{2}P_{3/2}$ cycling transition, repumping on the 280.4$\,$nm $^{2}S_{1/2}\leftrightarrow$ $^{2}P_{1/2}$ transition, coherent state manipulation, and resolved sideband cooling close to the motional ground state. Our systems serve as prototypes for applications in AMO requiring single-frequency, power-scalable laser sources at multiple wavelengths., Comment: 6 pages, 9 figures

A high-power optically-pumped vertical-external-cavity surface-emitting laser (VECSEL) generating 10.5 W of cw output power at 615 nm is reported. The gain mirror incorporated 10 GaInNAs quantum wells and was designed to have an emission peak in the 1230 nm range. The fundamental emission was frequency doubled to the red spectral range by using an intra-cavity nonlinear LBO crystal. The maximum optical-to-optical conversion efficiency was 17.5%. The VECSEL was also operated in pulsed mode by directly modulating the pump laser to produce light pulses with duration of ~1.5 µs. The maximum peak power for pulsed operation (pump limited) was 13.8 W. This corresponded to an optical-to-optical conversion efficiency of 20.4%.

The effects of unintentional boron contamination on optical properties of GaInP/AlGaInP quantum well structures grown by molecular beam epitaxy (MBE) are reported. Photoluminescence and secondary-ion mass spectrometry (SIMS) measurements revealed that the optical activity of boron-contaminated quantum wells is heavily affected by the amount of boron in GaInP/AlGaInP heterostructures. The boron concentration was found to increase when cracking temperature of the phosphorus source was increased. Boron incorporation was enhanced also when aluminum was present in the material.

We report a high-power VECSEL emitting

We report on the development of a high-power vertical-external-cavity surface-emitting laser (VECSEL) emitting around 1180 nm. The laser emitted 50 W of output power when the mount of the gain chip was cooled to -15°C. The output power was measured using a 97% reflective cavity end-mirror. The VECSEL was arranged to form an I-shaped cavity with a length of ~100 mm; the gain chip and a curved dielectric mirror (RoC=150) acting as cavity end mirrors. The gain chip was grown by molecular beam epitaxy (MBE) and incorporated 10 GaInAs/GaAs quantum wells. For efficient heat extraction, the chip was capillary bonded to a diamond heat spreader which was attached to a TEC-cooled copper mount. The maximum optical-to-optical conversion efficiency of 28% was achieved for 42 W of output power and -15°C mount temperature.

We report the first monolithic GaAs-based vertical external-cavity surface-emitting laser (VECSEL) operating at 1550 nm. The VECSEL is based on a gain mirror which was grown by plasma-assisted molecular beam epitaxy and comprises 8 GaInNAsSb/GaAs quantum wells and an AlAs/GaAs distributed Bragg reflector. When pumped by an 808 nm diode laser, the laser exhibited an output power of 80 mW for a mount temperature of 16 °C.

We present a master oscillator power amplifier (MOPA) system that comprises a mode-locked semiconductor disk laser (SDL) emitting at 1.33 μm and a bismuth-doped fiber amplifier. The mode-locked SDL was fabricated by wafer bonding an InP-based gain section with a GaAs-based distributed Bragg reflector (DBR) using (3-Mercaptopropyl)-trimethoxysilane. The bismuth-doped fiber amplifier was pumped with a continuous wave SDL emitting at 1.18 μm. The MOPA system produced pulses at a repetition rate of 827 MHz with a pulse energy of 0.62 nJ, which corresponds to an average output power of more than 0.5 W.

The analysis of novel vertical external-cavity surface-emitting laser (VECSEL) designed for simultaneous dual-wavelength emission is presented. Inhomogeneous optical pumping of the nonidentical quantum wells of the active region has been studied. The novel rate equations description of our VECSEL is presented taking into account a strong time-delayed feedback. Steady-state stability conditions and the dynamics of dual-wavelength lasing have been investigated. It appears that tendency to self-pulsation due to Q-switching at high pump power is avoidable by accurate modeling and epitaxial growth of the active region of the laser

Room temperature lasing operation at 599 nm for a AlGaInP/AlInP/GaAs edge-emitting laser structure is reported. The structure was grown on GaAs substrate and pumped optically with a 532 nm Q-switched laser. The lasing threshold for a 2 mm long and 25 μm wide ridge waveguide structure was 30 mW of average pump power. The orange output beam had an optical spectral width of 1.7 nm.

Self-assembled quantum dots (QDs) with low surface density and emission wavelength in a range suitable for coherent optical investigations are grown on GaAs(001) substrate by means of solid-source molecular beam epitaxy. We consider two QD systems: Stranski–Krastanow grown InAs/GaAs QDs and unstrained GaAs/AlGaAs QDs obtained by multi-step self-assembly from a template of InAs QDs. In both cases the QD density is tuned by suitably choosing the growth parameters of the InAs layer and controlled by means of atomic force microscopy and spatially-resolved photoluminescence (PL) spectroscopy. The emission wavelength of the as-grown InAs QDs is optimized by post-growth rapid thermal annealing (RTA) at temperatures between 750 and 990 ∘C. Remarkably, the PL-inhomogeneous broadening increases at the onset of the RTA-induced blue-shift and then narrows considerably. A simple calculation allows us to interpret this observation. By means of micro-PL we observe resolution-limited emission lines from single-QDs, demonstrating that the RTA treatment does not produce any deterioration of the structure quality. In contrast to InAs/GaAs QDs, the as-grown GaAs/AlGaAs QDs have optimum emission energy, and do not require any post-growth processing.

We report on photoluminescence (PL) studies of GaInP epilayers and GaInP/AlGaInP quantum well (QW) heterostructures grown by solid-source molecular beam epitaxy (SS-MBE) on GaAs substrates, which were cut exactly along the (1 0 0) plane or deliberately misoriented 10° towards [1 1 0], [1 1 1]A, and [1 1 0] directions. Closely optimal growth conditions were determined for the samples. The strongest emission from GaInP epilayers was obtained when growth temperature and phosphorus beam equivalent pressure (BEP) were around 520°C and 2×10 −5 mbar, respectively, quite independent of whether the substrate was cut along (1 0 0) or 10° off towards [1 1 1]A. This surface also produced the strongest emission from the QWs grown at 490°C with BEP≈1×10 −5 mbar. It was observed that the epilayers on the (1 0 0)-0° surfaces exhibited an enhanced alloy order effect, which red-shifted the PL spectra. Impurity oxygen, likely originating from the phosphorus charge, deteriorated emission especially from the misoriented surfaces.

The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

Effects of rapid thermal annealing (RTA) on deep-level defects have been studied for epitaxial layers of (Al 0.25 Ga 0.75 ) 0.52 In 0.48 P, doped with Si and Be, grown on (100) GaAs substrates by the solid-source molecular beam epitaxy method. It appeared that RTA treatment affected significantly the net carrier concentrations at temperatures higher than 700 °C. Several deep levels were found. It was also found that RTA induced a new deep level with activation energy of about 0.5 eV in n-AlGaInP and another level with activation energy of 0.75±0.06 eV in p-AlGaInP. Annealing caused a change in trap parameters of the DX -center. Such a behaviour is believed to be due to a change in defect configuration or defect clustering. RTA also increased the concentration of another Si-related defect. An increase in net acceptor concentration observed for p-AlGaInP correlates with a decrease in concentration of a deep level with activation energy of 1.30±0.10 eV. This level is suggested to influence device performance characteristics.

We demonstrate that a combination of ultrafast wafer bonded semiconductor disk laser and a bismuth-doped fiber amplifier provides an attractive design for high power 1.33 µm tandem hybrid systems. Over 0.5 W of average output power was achieved at a repetition rate of 827 MHz that corresponds to a pulse energy of 0.62 nJ.

We report on the development of a pulsed high-power frequency doubled vertical-external-cavity surface-emitting laser (VECSEL) with a peak output power of 14 W and emission spectrum near 588 nm. The semiconductor gain chip was grown by molecular beam epitaxy and comprised 10 GaInAs quantum wells. The gain structure was designed to be antiresonant at 1180 nm. The fundamental wavelength was frequency doubled to the yellow–orange spectral range using a 10-mm long critically phase matched lithium triborate nonlinear crystal, situated at the mode waist of the V-shaped laser cavity. The emission spectrum was narrowed down to FWHM of < 0.2 nm by employing a 1.5 mm birefringent filter and a 100-μm-thick etalon inside the cavity. By directly modulating the pump laser of the VECSEL, we were able to produce pulse widths down to 570 ns with average and peak output power of 81 mW and 14 W, respectively. The repetition rate was kept constant at 10 kHz throughout the measurements. The maximum peak power obtained was pump power limited. In comparison, at the same coolant temperature, a maximum of 8.5 W was achieved in continuous wave. The maximum optical-to-optical conversion efficiency (absorbed peak pump power to peak output power) was calculated to be 20–21 %.

We report on the use of a Semiconductor Disk Laser (SDL) as a seed laser for an Ytterbium-Doped Photonic Bandgap Fiber (Yb-PBGF) amplifier in a Master-Oscillator Power-Amplifier (MOPA) configuration. The SDL comprised a GaInAs/GaAs/GaAsP gain chip, a 1-mm-thick etalon for mode selection, and a 3-mm-thick birefringent filter for wavelength tuning. The fiber amplifier consisted of an Yb-doped core surrounded by a structure of periodically arranged germanium rods with a pitch of 10.2 μm, and to maintain the polarization, the fiber comprised two boron rods. The output of the MOPA-configuration was 31 W and the linewidth of the amplifier output was 149±31 kHz.

We report on the development of a high-efficiency frequency doubled vertical-external-cavity surface-emitting laser with an output power of 20 W and emission spectrum centered at 588 nm. The MBE-grown gain chip incorporated 10 GaInAs quantum wells and emitted in the 1180 nm range. The frequency conversion was achieved using a lithium triborate nonlinear crystal in an intra-cavity configuration. In addition to the nonlinear crystal, the V-shaped cavity also included a birefringent filter and an etalon for linewidth narrowing and wavelength tuning. The maximum optical-to-optical conversion efficiency obtained was ~28 % for 16 W of output power and the VECSEL had a tuning bandwidth of ~26 nm ranging from about 576 to 602 nm. We were also able to generate yellow pulses down to 570 ns duration by directly modulating the VECSEL’s pump laser.

We have studied growth of single GaInP layers and AlGaInP/GaInP QW heterostructures on GaAs substrates, which were misoriented 0°, 3°, 10°, and 15° from the (1 0 0) crystal plane toward 〈1 1 0〉. The samples were grown by solid source MBE (SSMBE), and were characterized by photoluminescence (PL) and the deep level transient spectroscopy (DLTS) to investigate their optical properties and nature of deep levels. The samples grown on highly misoriented substrates showed an increase of over 300% and 22% in PL intensity for the bulk GaInP and QW structures, respectively, when compared to nominally identical samples grown on GaAs(1 0 0)-0° substrates. It was also found that growth of AlGaInP on misoriented substrates required a smaller phosphorous beam equivalent pressure than what was necessary for growth on GaAs (1 0 0)-0°

We report on intracavity sum-frequency generation in a semiconductor disk laser operating simultaneously at the wavelengths of 986 and 1043 nm. An LBO crystal was used for nonlinear frequency conversion of the infrared radiation into the aquamarine sum-wavelength of 507 nm. Total converted power of 130 mW was obtained. The results suggest that a similar concept could be applied for difference-frequency generation to create a compact mid- infrared emitter operating at room temperature.

We report an optically pumped vertical external-cavity surface-emitting laser that is designed for emission at two wavelengths simultaneously. Single transverse mode continuous-wave (CW) operation is demonstrated at the wavelengths of 984 and 1042 nm. The device produces a CW optical power of 140 mW for the 984-nm component and 115 mW for the 1042-nm component, exhibiting over 10% efficiency. At a high pump power, self-pulsation of the components appeared on top of the CW-mode components. The maximum total output of 1 W was obtained at the pump power of 9 W.

A proof-of-principle study of a 1.97-µm Tm:Lusub2/subOsub3/subceramic disk laser, intracavity pumped by a 1.2-µm semiconductor disk laser, is presented. The demonstrated concept allows for improved pump absorption and takes advantage of the broad wavelength coverage provided by semiconductor disk laser technology. For thin disk lasers the small thickness of the gain element typically leads to inefficient pump light absorption. This problem is usually solved by using a complex multi-pass pump arrangement. In this study we address this challenge with a new laser concept of an intracavity pumped ceramic thin disk laser. The output power at 1.97 µm was limited to 250 mW due to heat spreader-less mounting scheme of the ceramic gain disk.

We review our results concerning the development of Semiconductor Disk Lasers with emission wavelength in the range of 1100-1200 nm. In particular, we highlight our recent demonstrations of SDLs with an output power of more than 20 W for emission around 1180 nm and corresponding frequency doubled power of more than 10 W at around 589 nm. The SDL gain chips utilize either dilute nitride (GaInNAs) or low-temperature GaInAs quantum wells.

We report a high power single-frequency 1178 nm laser combining an optically-pumped semiconductor disk laser and an Yb-doped photonic bandgap fiber amplifier. An output power of 31 W with

In this paper we report the development of an intra-cavity frequency doubled high power VECSEL emitting around 589 nm.

We report high power operation of a vertical external-cavity surface-emitting laser (VECSEL) operating around 1180 nm. The gain chip of the VECSEL comprises 10 strain-compensated GaInAs/GaAs quantum wells in a top-emitting configuration. A maximum output power of 23 W was achieved with a mount temperature of about 0 ‡C, and 20.5 W with the mount temperature of about 12 °C. By introducing a birefringent filter inside the laser cavity we demonstrate a tuning range of 67 nm. The gain chip was also used to construct a VECSEL for single-frequency operation. In this configuration, a maximum output power of about 11 W was recorded.

We demonstrate the first Tm-doped Lu2O3 ceramic laser utilizing disk geometry in the design of the active element. The ceramic 2-µm disk laser is pumped within the high-Q cavity of a 1.2-µm semiconductor disk laser.

This paper presents the development and narrow-linewidth characteristics of an optically-pumped vertical external-cavity surface-emitting laser emitting light near 1120 nm. The laser development is motivated by the need to achieve narrowlinewidth, frequency-stable laser emission near 280 nm for cooling of Mg + ions. The laser is capable of emitting ~0.8 W at 1118.542 nm in a less than 300 kHz linewidth.

We analyze the effect of strain compensation on the crystalline quality of InGaAs/GaAs quantum well gain mirrors that are designed for emission above 1100 nm. The gain mirrors used in this study were grown by molecular beam epitaxy and they utilize GaAsP strain compensation. The effect of strain compensation has been assessed by measuring the curvature of the wafers and by mapping photoluminescence to identify non-emissive dark areas. We present that about 70 % strain compensation is sufficient to prevent dark line defect generation for gain mirrors designed for up to 1170 nm operation. Rapid thermal annealing studies revealed that the strain compensation is efficient in preventing appearance of dark lines even for samples that have been annealed at temperatures as high as 700 °C for a considerable time. Finally, we demonstrate multi-watt operation at 1115-1190 nm using 70-90 % strain compensated gain mirrors.

Fundamental mode, ~100 ps, ~40 W optical pulses are demonstrated from a laser diode with a strongly asymmetric waveguide structure and a relatively thick (~0.1 μm) active layer driven with ~15 A, ~1.5 ns injection current pulses produced by a simple avalanche transistor circuit. Using this compact laser source, pulsed time-of-flight laser rangefinding measurements were performed utilizing a single-photon avalanche detector. The results show the feasibility of a very compact overall device with centimeter-level distance measurement precision and walk-error compensated accuracy to passive targets at tens to hundreds of meters in a measurement time of about ten milliseconds.

We review recent results concerning the development of dilute nitride based semiconductor disk lasers. We have demonstrated over 7.4 W of output power at the second harmonic wavelength (around 590 nm) using a β-BBO crystal. Over 10 W has been demonstrated at ~1.2 μm, and multi-watt output power has been achieved at 589 nm with narrow linewidth (δν < 20 MHz).

We have constructed a singly resonant, continuous-wave optical parametric oscillator, where the signal beam resonates and is amplified by a semiconductor gain mirror. The gain mirror can significantly decrease the oscillation threshold compared to an identical system with conventional mirrors. The largest idler beam tuning range reached by changing the pump laser wavelength alone is from 3.6 to 4.7 µm. The single mode output power is limited but can be continuously scanned for at least 220 GHz by adding optical components in the oscillator cavity for increased stability.

Sodium guide star lasers operating at 589 nm are commonly deployed in earth based telescopes. Next generation guide star lasers require sources with output power of more than 20 W, stable operation with narrow linewidth (< 5MHz), and high beam quality [1]. Frequency doubled semiconductor disk lasers (SDLs) are anticipated to fulfil the specifications owing to their high power, efficient intracavity frequency conversion [2], and possibility to directly modulate the output beam. In order to achieve fundamental emission at 1178 nm we have developed high quality GaInNAs/GaAs quantum well based gain mirrors [3]. Here we report on the development of a multiple gain element disk laser for generating narrow band radiation at 1178 nm.

We report recent developments of GaInNAs-based semiconductor disk lasers (SDLs) emitting at around 590 nm. GaInNAs/GaAs (dilute nitride) quantum-wells enable lasing at a wavelength of ∼1180 nm with reduced indium content and hence reduced lattice strain as compared to InGaAs quantum wells [1], leading to SDL operation with output powers of more than 11W using a single gain chip [2]. The importance of dilute nitride material system for generating high power yellow-orange radiation via frequency doubling of ∼1180 nm SDLs has been recently recognized [3]. In the current experiments we use a single gain mirror cavity (shown in Fig. 1) and investigate the conversion efficiency, power stability, and polarization of the frequency converted output beam. The SDL gain mirror had 10 GaInNAs QWs and was grown by molecular beam epitaxy (MBE). The gain chips were capillary-bonded to a wedged diamond heat spreader. An antireflective coating was deposited on top of the heat spreader to alleviate parasitic reflection from the surface of the wedged diamond. The component was attached to a water-cooled copper mount. For frequency doubling, a 4 mm long type-I critically phase-matched beta barium borate (BBO) crystal was placed inside the laser cavity (between folding mirror and the plane mirror).

Optical parametric oscillator (OPO) is a well-known nonlinear technique to convert laser light at shorter wavelengths to the middle infrared region, where normal laser sources are scarce. In particular, continuous-wave (cw) laser-like beams with narrow bandwidth, good tunability and high spectral brightness needed for spectroscopic applications are usually created using an OPO. A singly resonant (SR) design, where a near infrared signal beam resonates, can be constructed with a relatively simple setup and is capable of producing a narrow-linewidth, tunable idler beam in the middle infrared. This kind of source is highly desirable for spectroscopic applications, such as optically exciting selected vibrations of small organic molecules to detect, measure, or manipulate them.