Intense Quantum Well Intermixing Laser Technology Revolutionizes High Power Laser Diodes

Quantum Well Intermixing (QWI) is a fundamental semiconductor process used by Intense to set new standards for the performance, reliability, and manufacturability of high power laser diodes. QWI enables the integration of passive regions at the facets of laser diode emitters, arrays, and bars giving excellent performance, enhanced reliability, and superior manufacturing yield. The advance of QWI technology allows for the development of small form-factor, cost effective, and extremely versatile optical systems that can dramatically change the dynamics of existing products and create whole new market segments. The disruptive nature of Intense's revolutionary QWI laser technology is powering a wide range of laser diode products that require the precise delivery of optical energy, such as digital printing, advanced welding systems, and defense electronics.

QWI Revolutionizes the Reliability of Laser Diodes

Single mode semiconductor lasers are important for many precision applications, such as Computer-to-Plate (CtP) printing. Increased laser power and smaller form factors are being demanded in order to provide faster print speeds and lower costs.

High power multimode laser diode emitters, bars, and stacks are used in industrial and defense applications, including pumping solid state lasers, rangefinding, target designation, machining, and micro welding. High reliability, superior brightness, and enhanced power levels are needed for these increasingly demanding applications.

The power and reliability of a typical laser device are fundamentally limited by absorption in the facet region, giving rise to Catastrophic Optical Mirror Damage (COMD). A related major issue with conventional high power lasers is filamentation, which creates a hot-spot on the laser facet, limiting the optical power and causing COMD.

In response to the more sophisticated requirements of today's markets, Intense has developed an advanced QWI process to increase the Quantum Well (QW) band-gap of a semiconductor laser in a controlled and very precise manner, creating active and passive sections in the same laser cavity. The QWI process is illustrated in Fig.1 where a slight disordering of the QW region of a GaAs/AlGaAs laser results in a widened band-gap. Fig. 2 shows a schematic diagram of a QWI enhanced laser diode.

Non-Absorbing Mirrors (NAMs) are created by the Intense QWI process, passivating the facet regions of the laser. Semiconductor lasers with NAMs have been shown to operate at much higher powers than conventional devices. For example, a dramatic improvement in single mode power can be achieved by including NAMs with a large QWI shift such that the risk of COMD is negated, giving a high performance single mode laser that can operate at enhanced optical power (>1W) with exceptional reliability (Fig.3). By comparison, a conventional laser without NAMs suffers COMD at low optical power.

The Intense QWI process has created a new standard in the reliability and performance of semiconductor laser diodes. In excess of 20 million total emitter hours have been collected at high optical powers. The exceptional lifetime enables very large arrays of up to 100 laser elements to be manufactured with per emitter lifetimes measured in millions of hours in Continuous Wave (CW) or pulsed operation.

In addition, Intense has developed a unique range of high power lasers using QWI technology that have extremely high optical power (over 10W from a 100µm wide emitter) and brightness with exceptional reliability by using a modified ridge waveguide structure and NAMs at the facet region.

QWI Enables High Yield Laser Array Manufacture

The NAM regions have low optical loss and are fabricated so they occupy a significant fraction of the length of the cavity. This relaxes the cleave tolerances during fabrication, allowing for a high yield process during manufacture. Large arrays of up to 100 laser elements can be integrated onto a single chip (see Fig. 4) with excellent laser parametric uniformity (see Fig. 5).

These large multi-element laser chips, together with drive ASICs and micro-optics, form the building blocks of complex optical systems, all packaged inside robust modules with a small form-factor.

Exceptional Uniformity & Beam Control

NAMs bring further advantages to many applications, including high precision printing, since the facet regions remain relatively cold during operation, giving an exceptionally well controlled single mode beam in terms of spot size and pointing stability. The exceptional uniformity and beam control of each laser element in a large array enables very high resolution imaging to be achieved.

Wide Applicability

The QWI process has been developed to cover a wide range of laser wavelengths (630-1650nm) allowing a broad range of products to be developed across many different market spaces.

Driving Innovation

Intense QWI lasers are driving a revolution in new product development across a wide spectrum of applications, from very high resolution thermal CtP and electrophotographic (EPG) printing, to lower resolution printing such as coding and marking. Intense is also penetrating the high power laser market, with a unique range of QWI lasers with high reliability, superior brightness, and enhanced power levels.

A disruptive technology, QWI is changing the basis of competition, allowing the pursuit of radical improvements in cost, performance, form-factor, and reliability for existing products as well as creating new markets.

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Fig. 1: A schematic diagram of the band-structure and epitaxy of a non-processed vs. a QWI processed quantum well.

Fig. 2: A schematic diagram of a QWI enhanced laser diode, with reduced facet heating enabling high-power, high-reliability operation.

Fig. 3: Optical power versus drive current for single mode laser diodes with NAMs.

Fig. 4: An image of a monolithic single chip containing 100 high power, single mode lasers. The NAM regions are the green areas either side of the gold p-metal contact.

Fig. 5: Single mode power is plotted for each laser in a wide array. The power is measured under CW operation at 300mA and shows excellent uniformity.

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