2-Wavelength Laser Diodes with Novel Real Index Guide for High Temperature, Low Current Operation

2010-03-01

ROHM Co., Ltd. has announced the development of three 2-wavelength laser diodes that provide stable operation, even at high temperatures, due to significantly reduced operating current compared to conventional products. Conventional laser diodes used for playback in DVD and CD drives use a Loss Guide waveguide structure. In contrast, ROHM's new laser diodes employ a Real Index Guide that features low light absorption loss and outstanding reliability, resulting in dramatically reduced operating current and stable operation.

Laser diode waveguide structures come in two types: Loss Guides and Real Index Guides. Loss Guides, although simple and inexpensive, have a tendency to absorb light within the device during laser oscillation and are unstable at high temperatures. Real Index Guides, on the other hand, operate stably with no light absorption. However, the manufacturing process is complex and the production costs high, making them ideal primarily for use as high-output lasers. In response to this ROHM has succeeded in developing a highly reliable 2-wavelength laser for low-output applications such as DVD/CD playback by utilizing an optimized, high-efficiency Real Index Guide with no light-absorption loss.

Although the DVD/CD drive market has matured and the shift has been made towards Blu-ray discs, DVD/CD lasers are still built into Blu-ray recorders and players for backwards compatibility. They are mounted separately from the Blu-ray laser, since the wafer materials differ, making it difficult to mount them on a single chip.



Pricing (For sample shipments)  : 1000yen/unit (RLD2WMUL3), 800yen/unit (RLD2WMFL3),
   2000yen/unit (RLD2WMNL2)
Availability  : OEM Quantities
  1. RLD2WMUL3 and RLD2WMFL3: Ideal for CD/DVD playback in gaming consoles, portable devices, and slim drives
    Conventionally, lasers for game consoles and portable devices guarantee operation only up to 75ºC. In contrast, ROHM's RLD2WMUL3 and RLD2WMFL3 reduce current consumption by 30% and 46% during DVD and CD playback, respectively, ensuring stable operation up to 80ºC. This decreases power consumption and simplifies thermal countermeasures, resulting in lower set costs. Two package types are available - a high heat-dissipation 5.6Ø CAN package (RLD2WMUL3) for automotive applications and a resin frame package (RLD2WMFL3) for portable consumer devices.
     
  2. RLD2WMNL2: Optimized for CD/DVD playback in car DVD drives and car navigation systems
    Proprietary, brand-name car DVD drive and navigation systems normally require a guaranteed operating temperature range up to 85ºC. In order to counter light absorption loss at high temperatures in conventional laser diodes, the chip length (resonator length) and oscillator wavelength are typically lengthened. However, DVD drives optimized for the 655nm wavelength are susceptible to skipping and other problems during data reading with longer wavelengths (i.e. 670nm). This problem is particularly evident when reading long-wavelength media such as DVD-R discs which utilize an organic layer that changes color, in which the permissible wavelength range is narrow.
    The RLD2WMNL2 reduces operating current by 44% during DVD use and 43% during CD playback and is capable of stable operation at high temperatures without increasing chip length or oscillation wavelength, preventing skipping and malfunctions while simplifying set design. In addition, the completely sealed CAN package with glass window ensures high reliability, even under severe conditions.
2-Wavelength Laser Diodes for DVD/CD Playback (RLD2WMUL3 / RLD2WMFL3 Series)
(PDF:702KB)
Low Output 2-Wavelength Laser Diodes for DVD/CD Playback (RLD2WMNL2 Series) (PDF:417KB)

■Additional Data

1.Product Comparison: If vs. Po (at 85ºC)

Product Comparison: If vs. Po (at 85°C)



2.Primary Specifications

RLD2WMFL3 (Frame Package) and RLD2WMUL3 (Open-Type CAN Package)

Part No. Absolute Maximum Ratings
(Tc = 25ºC)
Electrical and Optical Characteristics
(Tc = 25ºC)
Optical Output
(mW)
Reverse Voltage
(V)
Operating Temp.
(℃)
Storage Temp.
(℃)
Oscillation Wavelength
(nm)
Threshold Current
(mA)
Operating Current
(mA)
Operating Voltage
(V)
Monitor Current
(mA)
Parallel Divergence Angle
(deg)
Perpendicular Divergence Angle
(deg)
RLD2WMUL3 7/7 2/2 -10 to +80 -40 to +85 658/782 13/12 18/17 2.2/1.8 0.25/0.25 8.5/10 27/32
RLD2WMFL3 7/7 2/2 -10 to +80 -40 to +85 658/782 13/12 18/17 2.2/1.8 0.15/0.17 8.5/10 27/32

RLD2WMNL2 (Glass-Sealed CAN Package)

Part No. Absolute Maximum Ratings
(Tc = 25ºC)
Electrical and Optical Characteristics
(Tc = 25ºC)
Optical Output
(mW)
Reverse Voltage
(V)
Operating Temp.
(℃)
Storage Temp.
(℃)
Oscillation Wavelength
(nm)
Threshold Current
(mA)
Operating Current
(mA)
Operating Voltage
(V)
Monitor Current
(mA)
Parallel Divergence Angle
(deg)
Perpendicular Divergence Angle
(deg)
RLD2WMNL2 7/7 2/2 -30 to +85 -40 to +85 663/785 18/15 24/20 2.3/1.8 0.25/0.25 10/10 28/32

■Terminology

  • Waveguide
    A structure that contains current and light to produce laser oscillation with a high degree of directivity.
  • Loss Guide and Real Index Guide
    A Loss Guide is configured by inserting a current block layer that absorbs light inside an active layer. A Real Index Guide, on the other hand, is transparent with respect to light. Light lost to absorption is greatly reduced with a Real Index Guide, making it possible to produce laser oscillation at lower currents.
Products Laser Diodes