Not all diode lasers are the same:
QPC Lasers provide the ultimate in brightness, spectral purity and reliability with proprietary epitaxial features grown right into the semiconductor of diode lasers.
Only QPC has Brightlock® and Brightlase®!
Brightlock® Diodes: On-Chip Spectral Stabilization
When loosely specified output wavelengths and line widths just won’t do the job, Brightlock® Diode Lasers is the solution!
Conventional diodes lack spectral control, with linewidths as great as several nm and wavelengths that drift with temperature by 500 pm/°C or more. Bragg gratings inserted into the external optical train offer stabilization, but at the cost of increased complexity, reduced operating temperature range, degraded long term stability, and increased price. Additionally, they do not scale to high powers. Lastly, grating stabilized diodes cannot be tuned to accurately match narrow absorption lines.
QPC Lasers’ Brightlock® family of diode lasers provide spectral stabilization that is intrinsic to the architecture of the diode. Diffraction grating stabilization features are embedded in a single fabrication step into the semiconductor structure of an entire wafer consisting of hundreds of diodes. In essence, the need for optically coupling and aligning external grating stabilizers is eliminated, along with the problems that external stabilization creates.
Brightlock® offers sub-nm spectral widths and center wavelength specification, and spectral temperature tuning coefficients around the “sweet spot” of 100 pm//°C. As a result, Brightlock® provides sufficient range for perfect wavelength matching while minimizing temperature drift.
Brightlase® Lasers: Monolithic Facet Protection
When you need reliable, long term operation at high power, turn to Brightlase®!
Diode lasers are the most versatile and compact sources of laser light available: they can convert kilowatts of electricity directly to laser light at a wide range of wavelengths with high efficiency at a fraction of the cost of competing lasers. However, the optical brightness of diode generated beams lags behind those of solid-state and fiber lasers, putting some important applications out of reach.
This limitation is due to the fact that diodes suffer damage if operated at optical fluxes beyond several MW/cm2; at these levels the heat generated by residual absorption of the generated beam literally “cooks” the output facet of the diode, causing premature burnout. To ensure long operating lifetimes, diodes are generally operated at a fraction of their potential maximum power, or spread the beam out over a large area, both of which reduce brightness.
QPC Lasers’ Brightlase® technology breaks through this barrier by monolithically embedding protective “windows” into the semiconductor structure of the diode itself. These features are fabricated of semiconductor layers specially engineered to minimize optical absorption and are epitaxially grown into the semiconductor itself; they are not external coatings deposited on the surface of the diode as in competing facet protection approaches. Brightlase® greatly reduces the temperature of the diode facets, allowing power and brightness increases of as much as three times in some cases.
QPC MOPA Lasers:
High Power Single Frequency/Diffraction-Limited Diode Lasers
Combining the beam quality and spectrum of a gas or fiber laser with the efficiency and compactness of a diode.
Some important applications require beams with near diffraction-limited beam quality, and some require temporally coherent, single frequency beams as well. Conventional high power diodes are neither diffraction limited nor single frequency because their large resonant cavities support multiple modes of oscillation simultaneously. A typical diode’s power is divided between 10 to 20 distinct groups of “lateral” modes, each with its characteristic radiation pattern and sub-mode frequencies. With the exception of the lowest order (or “fundamental”) mode, these are highly divergent and with beam qualities several times worse than the diffraction limit.
Master Oscillator Power Amplifier (MOPA) diodes have the unique ability of generating high power output beams that are both diffraction-limited and single frequency. MOPA diodes are comprised of two sections that are monolithically integrated onto the same chip. This includes a low power, distributed feedback laser whose output seeds a high power semiconductor optical amplifier. The beam generated by the distributed feedback seed laser is diffraction limited and single frequency, and this beam is amplified by 100 times or more without significant loss of beam quality or spectral purity. Average powers up to several tens of Watts, and pulsed powers exceeding 100 W can be generated without loss of beam quality.
MOPA diodes were invented more than 30 years ago by members of our technical staff, and QPC has more experience with this technology than the rest of the world combined. We have many years of experience with MOPA diodes deployed in commercial applications.
QPC Eye-Safe Wavelength Monolithic Stack Diode Lasers: High Power and Brightness at Low Drive Current
Cut drive current by 2X (or more) with monolithic stack diode lasers from QPC!
Fundamental physics dictates that diode lasers create only one photon for every electron of drive current, and high power diodes are consequently high current, low voltage devices. This is undesirable in applications such as battery powered consumer products such as home skin care lasers, where high current draw results in short battery life, and is even less acceptable in pulsed LIDAR and range finding, where high currents result in high Joule (I2R) losses.
QPC Lasers pioneered diode lasers designs that bypass this limitation by monolithically stacking multiple laser junctions on top of each other in such a fashion as to connect them in electrical series. Each injected drive current electron does multiple duty generating a photon every time that it passes through a junction, so that for example, a triple junction can create three photons for every electron injected. Firstly, compared to a conventional single junction diode, the required drive current is reduced by a factor corresponding to the number of junctions in the stack. Plus, when properly designed, the operating voltage is not much higher than a conventional single-junction diode.
Furthermore, a key component of this technology is the optimal design of the layers separating the adjacent diode layers. This effectively converts the polarity of charge carriers while maintaining high brightness, and also minimizes both resistive and optical absorption losses. QPC Lasers has many years of experience with this technology with hundreds of thousands of multi-junction monolithic stack eye-safe diodes in the field.
