New Products FLD6A4TK High-Power Red Laser Diodes for Recordable DVD Systems FLD6A4TK FLD6A4TK is a low-aspect ratio, high-power, red laser diode designed for digital versatile disk systems known as DVD-R/RW/RAM. It delivers a high laser output of 90mW with a low aspect ratio of 1.4. Product Description Module Characteristics Now that DVD-ROM/ DVD players and high-speed telecom networks are widespread, the growing demand for rewritable DVDs gives strong incentive to DVD manufacturers to produce devices with high-speed rewriting capabilities. The implementation of high speed rewriting requires higher optical power at the beam spot on media. The efficient way to accomplish this is to design them with a low-aspect ratio beam in order to provide a near-perfect circle FFP (farfield pattern of beam). FUJITSU has succeeded in the commercialization of FLD6A4TK, a high-power, red laser diode that meets these requirements. Fig. 1 provides a device outline drawing. This device is available in the same 5.6mm standard package used for CD lasers. The polarity is compatible with a floating type and a grounding type. Table 1 lists the absolute maximum ratings, and Table 2 lists the electrical and optical characteristics. Fig. 2 shows the pulse I - L characteristics. The operating conditions include a pulse width of 100ns and a duty cycle of 50%. As the figure indicates, at Tc (operating case temperature) 0 to 70 , kink-free, 90mW or higher optical output is available. Fig. 3 shows the FFP (Far-Field Pattern) vs. optical output. Product Features Photo 1 External View ■ High power: 90mW (Pulse output 100ns, Duty cycle 50%) ■ Low aspect ratio: 1.4 ( : 17°, //: 12°) ■ Low operating current: Iop 70mA (CW 40mW) ■ Peak oscillation wavelength: 662nm (max.) ■ Operating temperature: 70 ■ 68 (max.) 5.6mm standard package FIND Vol.20 No.4 2002 New Products Single-peak, stabilized beams are achieved in the CW (continuous wave) state at 5 to 50mW. The optimized design of the chip waveguide structure ensures an aspect ratio (ratio to //) of 1.4 and beam divergence angles of (perof pendicular) 17° and // (parallel) 12°. This results in a nearround beam distribution. Fig. 4 shows the threshold current Ith vs. the operating case FLD6A4TK temperature. As the figure indicates, the use of a real refractive index-guided structure design for the chip reduces the Ith to a very small value only 25mA at Tc (op) 25 . Fig. 5 shows the peak oscillating wavelength vs. the operating case temperature. The device is designed to offer a peak oscillating wavelength of 662nm max. (at Tc (op) 25 ) for application to the DVD-R media. Figure 1 Product Outline Drawing Table 1 Absolute Maximum Ratings Table 2 Electrical and Optical Characteristics 2002 No.4 FIND Vol.20 69 New Products FLD6A4TK Figure 2 Pulse I - L Characteristics Fig. 6 shows the RIN (Relative Intensity Noise) vs. the optical feedback ratio. The measurements were performed under the following conditions: Tc (op) 25 , optical output 5mW, Iop 8mA (difference in Iop between when highfrequency modulation is set ON and OFF) and modulation frequency 320MHz. Fig. 7 shows the RIN vs. modulation frequency for the optical feedback ratio fixed at 2%. In all the conditions, RIN is -130dB/Hz or less, confirming that RIN values are accept✱ able for application to optical disks. Figure 3 FFP vs. Optical Output 70 FIND Vol.20 No.4 2002 New Products FLD6A4TK Figure 4 Threshold Current vs. Case Temperature Figure 6 RIN vs. Optical Feedback Ratio Figure 5 Oscillating Wavelength vs. Case Temperature Figure 7 RIN vs. Frequency 2002 No.4 FIND Vol.20 71