Susanne Pawlik

Diode-pumped passively mode-locked Nd:YVO/sub 4/ lasers with 40-GHz repetition rate

We present two different diode-pumped passively mode-locked Nd:YVO/sub 4/ lasers with a repetition rate of 40 GHz. This is the highest repetition rate demonstrated so far with diode-pumped 1-/spl mu/m solid-state lasers. The first laser design allows short pulses of 2.7-ps duration whereas the second laser design is optimized for high average output power of up to 288 mW. We compare both design approaches and show that there is a tradeoff between output power and pulse duration.

Further development of high-power pump laser diodes

AlGaAs/InGaAs based high power pump laser diodes with wavelength of around 980 nm are key products within erbium doped fiber amplifiers (EDFA) for todays long haul and metro-communication networks, whereas InGaAsP/InP based laser diodes with 14xx nm emission wavelength are relevant for advanced, but not yet widely-used Raman amplifiers. Due to the changing industrial environment cost reduction becomes a crucial factor in the development of new, pump modules. Therefore, pump laser chips were aggressively optimized in terms of power conversion and thermal stability, which allows operation without active cooling at temperatures exceeding 70°C. In addition our submarine-reliable single mode technology was extended to high power multi-mode laser diodes. These light sources can be used in the field of optical amplifiers as well as for medical, printing and industrial applications. Improvements of pump laser diodes in terms of power conversion efficiency, fiber Bragg grating (FBG) locking performance of single mode devices, noise reduction and reliability will be presented.

9xx high-power broad-area laser diodes

In this communication we report on the performance characteristics of Bookham’s latest generation of 915-990 nm broad area single emitter (BASE) laser diodes with around 90 μm wide aperture. Representative high power devices in the wavelength range of 950-960 nm, mounted p-side down onto expansion matched assemblies using our highly reliable AuSn-solder technology, reveal a high slope efficiency of around 1.05 W/A during CW operation at 25°C heat sink temperature. Coupling efficiency into multi-mode fiber with 0.15 or 0.22 numerical aperture exceeds 93% mainly due to the low vertical divergence of the laser beam. In addition, low laser threshold and series resistance enable more than 62% maximum wall plug efficiency of the present generation of the laser diodes. Preliminary tests of new prototypes reveal already excellent performance characteristics of the next generation device with up to 19.9 W light output power in pulsed operation and 16 W for thermally limited CW operation.

Synchronously pumped optical parametric oscillator with a repetition rate of 81.8 GHz

We present a singly resonant synchronously pumped optical parametric oscillator with a record-high pulse repetition rate of 81.8 GHz. It generates up to 0.9 W of signal average output power at a wavelength of 1569.7 nm. The pulses have a duration of 2.4 ps and are nearly transform-limited. The device is wavelength tunable from 1541.4 to 1592.2 nm. The tuning range could be easily extended by the use of a multiperiod periodically poled LiNbO/sub 3/ crystal.

Passively mode-locked 1.3-/spl mu/m multi-GHz Nd:YVO/sub 4/ lasers with low timing jitter

We demonstrate diode-pumped passively mode-locked 1.34-/spl mu/m Nd:YVO/sub 4/ lasers with repetition rates of 5 and 10GHz. Passive mode locking is achieved by using a novel GaInNAs-based saturable absorber mirror. Phase noise measurements prove the low timing jitter that can be obtained with this kind of lasers.

980 nm single mode modules yielding 700 mW fiber coupled pump power

Fiber coupled light output power of highly reliable single mode laser diodes with an emission wavelength of around 980 nm has been increased by 40% as compared to former results. The devices reach in excess of 1.3 W ex-facet CW light output power with up to 60% power conversion efficiency and exhibit a vertical far-field of around 21/spl deg/. The maximum fiber coupled CW light output power amounts to more than 700 mW. The devices are designed to satisfy the stringent requirements of future cost efficient uncooled applications as well as the high power market of broadband multi channel networks.

Optical parametric oscillator with a pulse repetition rate of 39 GHz and 2.1-W signal average output power in the spectral region near 1.5 µm

We present a singly resonant, synchronously pumped optical parametric oscillator with a record-high repetition rate of 39 GHz. The transform-limited 2.2-ps pulses at 1570 nm have as much as 2.1-W average output power. The all-solid-state pump source is based on a diode-pumped passively mode-locked 39-GHz Nd:YVO4 laser and an efficient ytterbium-doped fiber amplifier.

Highly efficient 980 nm single mode modules with over 0.5 Watt pump power

We present narrow beam divergence InGaAs/AlGaAs 980 nm ridge waveguide laser diodes with over 1 W CW-rollover power. Together with superior power conversion efficiency a maximum fiber-coupled light output power of over 0.5 W has been reached.

Recent developments for BAR and BASE: Setting the Trends

Bars with high and low filling factors serve the different schemes for beam transformation and fiber coupling. We report on highly efficient 8xx bars for operation in excess of 100 W and reliable broad-area single-emitter lasers (BASE) with 90 um aperture being capable to deliver in excess of 10 W from a 105 um core fiber. For 9xx bars we present solutions with power levels per device ranging from 60 W to 300 W corresponding to linear power levels beyond 8.5 W per 100 um stripe width indicating convergence of BAR and BASE devices. Life test results for these devices will be shown and high brightness fiber coupled solutions will be discussed.

Broad area single emitter (BASE) modules with improved brightness

High power pump modules are used for industrial as well as telecom applications such as for fiber lasers and cladding pumped erbium doped fiber amplifiers (EDFA) [Lichtenstein, N., et al., 2004]. Key element of a pump module is a single emitter laser diode, which normally has an aperture of around 90 mum, in order to provide best coupling into an optical multi-mode fiber with a 105 mum core diameter. Increasing the brightness of the pump module lends additional flexibility in the design of fiber lasers and amplifiers and enables higher output power. In this communication we report on two approaches to increase the brightness of our latest generation of high power pump modules. Within the first approach the electro-optical performance of the single emitter laser diode is improved by optimizing Bookhams mature chip technologies such as InGaAs/AlGaAs structures grown by MBE, the ridge-waveguide manufacturing process, the E2 facet passivation and the mounting technology. The combination of improved chip design and new coupling scheme leads to reliable broad area modules with outstanding brightness.