M Saarinen

High-speed resonant cavity light-emitting diodes at 650 nm

State-of-the-art resonant cavity light-emitting diodes (RC-LEDs) optimized for short-haul communication systems on polymethyl methacrylate (PMMA) plastic optical fiber (POF) are presented. The devices, emitting in the 650-nm wavelength range, are achieving, under different structure and working regime variants, high output power (15 mW), high external quantum efficiency (9.5%), record small-signal modulation bandwidth (f/sub -3/ /sub dB/ UP to 350 MHz), error free back-to-back transmission rates beyond 622 Mb/s, adjustable far-field pattern and good coupling efficiency into step index plastic optical fibers with reasonably large tolerances and without using auxiliary optics. The paper discusses the design concepts, modeling approaches, fabrication issues and performance characteristics of monolithic RC-LEDs emitting at 650 nm.

Broadband semiconductor saturable absorber mirrors in the 1.55-/spl mu/m wavelength range for pulse generation in fiber lasers

Broadband low-loss semiconductor saturable absorber mirrors (SESAMs) in the 1.55-/spl mu/m wavelength range were monolithically grown by solid source molecular beam epitaxy using a Burstein-Moss blue-shifted Ga/sub 0.47/In/sub 0.53/As-InP distributed Bragg reflector. Absorbers with fast and slow temporal responses were used to start up and to stabilize a stretched pulse mode-locked fiber laser. Reliable operation at a fundamental repetition rate was obtained without multiple pulse break-up with pulse energy of over 250 pJ.

Annealing of the deep recombination center in GaInP/AlGaInP quantum wells grown by solid-source molecular beam epitaxy

Time resolved photoluminescence and deep level transient spectroscopy have been used to monitor the effect of rapid thermal annealing on bulk GaInP and GaInP/AlGaInP quantum wells grown by solid source molecular beam epitaxy similar to those used in 650 nm range lasers. Following rapid thermal annealing at temperatures up to 875 °C, reductions in the concentration of several deep level traps are observed. Correlation of these data with photoluminescent intensity and lifetime measurements indicate that the defect labeled N3, 0.83 eV below the conduction band, is the dominant recombination center. The combination of these two transient spectroscopy measurement techniques is therefore not only able to measure the change in deep level concentration, but also to correlate this change with improved carrier lifetimes and, ultimately, reduced threshold current densities in quantum well lasers. There is also evidence to suggest that this same defect, possibly a phosphorous vacancy or a related complex, plays an im...

Light-emitting diode emitting at 650 nm with 200-MHz small-signal modulation bandwidth

State-of-the-art modulation bandwidths are presented for multiquantum well resonant cavity light emitting diodes (RCLEDs) emitting at 650 nm. 84-/spl mu/m size epoxy coated RCLEDs have a 1.4-mW (CW) output power and a small signal modulation bandwidth of 200 MHz at 40 mA bias. 150-/spl mu/m diameter devices yield 3.25-mW and 150-MHz bandwidth at 70-mA bias. An open eye-diagram at 622 Mb/s achieved for the 84-/spl mu/m device makes it very attractive for SONET OC-12 data communication links.

Influence of deep level impurities on modulation response of InGaP light emitting diodes

The effect of deep level impurities on static and dynamic properties of InGaP-based light emitters grown by all-solid-source molecular-beam epitaxy is analyzed. The improvement of the output power and the decrease in modulation bandwidth induced by the burn-in process are explained by the recombination enhanced annealing of one deep level trap. This assumption is experimentally proven through comparison of small-signal analysis for resonant cavity light-emitting diodes operating at 650 nm and deep level transient spectroscopy results. Finally, the concentration of the midgap recombination center N3 in the active region is shown to play an important role in the performance of the InGaP devices.

Temperature behaviour of resonant cavity light-emitting diodes at 650 nm

Performance characteristics of resonant cavity light-emitting diodes operating at the wavelength of 650 nm have been studied. It has been shown that a variation in device temperature significantly modifies the far-field pattern and thus the fibre coupling efficiency, due to a cavity detuning effect. Temperature dependences of output power and emission wavelength are also studied. Modulation bandwidth of >120 MHz and light power of 2 mW (cw) have been achieved for 84 µm devices driven at a 40 mA current. Accelerated ageing tests for 36 000 device hours indicate no degradation in output power.

High-power 600-nm-range lasers grown by solid-source molecular beam epitaxy

This paper presents the performance characteristics and reliability data of AlGaInP-based VISIBLE laser diodes emitting at the wavelengths from 630 to 670 nm. The lasers are grown by toxic gas free solid source molecular beam epitaxy.

Dual-wavelength generation by vertical external cavity surface-emitting laser

A high-power dual-wavelength AlGaInAs / GaAs laser operating in a vertical external-cavity surface emitting geometry, grown by molecular beam epitaxy, is reported. The active regions of the laser are separated by an optical long-wave-pass filter to prevent absorption of short-wavelength radiation in the long-wavelength gain area. The maximum output power achieved at 15 degrees C was 0.75 W at lambda approximately 966 nm and 1.38 W at lambda approximately 1047 nm for the pump power of 21.2 W.

Resonant cavity light emitting diode for a polymer optical fibre system

In this paper we review the recent development of resonant cavity light emitting diodes (RC-LEDs), intended for short-haul polymer optical fibre (POF) data transmission systems. The RC-LEDs with emission windows of 84 μm in diameter, suitable for standard POFs, exhibit bandwidths up to 200 MHz and light power of 3 mW (cw). The maximum external quantum efficiency is 9.5%. Larger devices, 500 μm in size, launch light power up to 15 mW. Record high transmission rates, 622 Mbit s−1, with bit-error rate <1×10−11 have been demonstrated for a 1 m long step-index POF. The devices are robust. Neither sudden unexpected failure, nor gradual power degradation has been observed after operation under accelerated ageing conditions for about 100000 device-hours. The alignment tolerance of the coupling efficiency is found to be very large, ±0.5 mm in all x–y–z, directions, suggesting that fibre pigtail packaging is inexpensive.

Resonant cavity light-emitting diodes at 660 and 880 nm

Abstract Resonant cavity light-emitting diodes (RCLEDs) operating at λ≅660 nm and λ≅880 nm have been fabricated and studied. The RCLED layer structures consisted of 1−λ thick cavities sandwiched between AlGaAs distributed Bragg reflectors. The cavities were detuned to improve temperature stability and light extraction. The temperature induced red-shifts in the peak emission wavelength were found to be 0.14 and 0.22 nm °C−1 for the 660- and 880-nm devices, respectively.