24-GHz modulation bandwidth and passive alignment of flip-chip mounted DFB laser diodes

High-frequency lasers have been flip-chip mounted on silicon motherboards. Small-signal modulation bandwidths around 24 GHz were obtained. It was shown that the bandwidth was not limited by extrinsic parasitics associated with the mounting scheme. Lasers were passively aligned to single mode fibers in V-grooves with the self-aligning solder bump technique. By passive alignment 50% of maximum coupling efficiency obtained by active alignment was achieved.     

Transmission characteristics of DFB laser modules for analogapplications

Analog transmission characteristics of highly linear 1.3- and 1.55-μm distributed feedback (DFB) laser modules are described. To obtain high-power and high-performance DFB lasers, the bias dependence of distortion characteristics is discussed. The carrier-to-noise ratio, the composite second-order distortion, and the composite triple beat of the DFB laser module which is developed for analog CATV applications are presented. The analog transmission characteristics, such as CNR degradation, after fiber transmission, dispersion-induced distortion, and the influence of reflection, have been made clear. The stable high linearity of the DFB laser also has been confirmed by the composite distortion measurement under an accelerated aging test     

Packaged 1.55 μm DFB laser with 25 GHz modulation bandwidth

25 GHz modulation bandwidth is achieved from a fully packaged 1.55 μm DFB laser, using devices with p-doped compressively strained MQW active regions and large negative wavelength detuning. Devices on submounts show a record bandwidth of 26 GHz, limited by device and bonding parasitics. Resonance frequencies of over 26 GHz are measured     

12 GHz FM bandwidth for a 1530 nm DFB laser

The FM response of a 1530 nm DFB laser has been measured using a novel birefringent fibre interferometer. The FM response is flat out to 12 GHz when operated at 9 mW/facet, corresponding to a linewidth of 15 MHz, and there is a 15-25 ps delay between the FM and AM responses     

Light-emitting diodes with a modulation bandwidth of more than 1 GHz

The design principle and the fabrication of high-speed l.e.d.s with a 3dB modulation bandwidth in the gigahertz range is described. The modulation characteristic, radiance and spectrum have been measured. The results demonstrate that these l.e.d.s are suited as light generators in optical transmission systems with a bandwidth in excess of 1 GHz.     

40-GHz dual-mode-locked widely tunable sampled-grating DBR laser

Generation of 40-GHz alternate-phase pulses is demonstrated using a dual-mode-locked sampled-grating distributed Bragg reflector laser. More than 10-dB extinction and >20-dB sidemode suppression ratio is measured over the >40-nm tuning range of the laser. Based on captured phase noise spectra, the timing jitter is estimated in the 0.35-0.41-ps range. The demonstrated dual-mode laser would form an attractive basis for an integrated 40-Gb/s return-to-zero transmitter.     

Very large bandwidth strained MQW DFB laser at 1.3 μm

A 3-dB bandwidth of 20 GHz has been demonstrated for a compressively strained multiquantum well InGaAsP-InP DPB laser operating at 1.3 μm. The laser displayed superior static performance including very low threshold current (~8 mA), high external quantum efficiency (0.44 mW/mA), high CW output power (>60 mW) and high temperature operation     

Bidirectional 10-GHz optical comb generation with an intracavityfiber DFB pumped Brillouin/erbium fiber laser

We present multiwavelength and bidirectional operation of a novel Brillouin/erbium fiber ring laser. Multiwavelength operation is seeded by an Er³⁺:Yb³⁺ fiber distributed-feedback (DFB) laser inserted into the ring cavity. We realized lasing at up to eight wavelengths separated by 10.6 GHz     

1064-nm DFB laser diode modules applicable to seeder for pulse-on-demand fiber laser systems

Semiconductor DFB (Distributed feedback) laser diodes with an operating wavelength of 1064 nm, which is suitable for pulse-on-demand fiber laser, have been developed. The stable performance of CW and nanosecond/picosecond pulsed operation is reviewed. By applying gain-switching operation with a simple direct modulation technique, 50-ps pulse generation with a stable spectral single-mode property was obtained. For the efficient amplification of the obtained 50-ps pulse, a monolithic semiconductor optical amplifier (SOA) was integrated into the DFB lasers. An improved peak power of 300 mW at 50-ps pulse was observed with limited optical noise injection when the synchronous modulation technique of the DFB and the SOA was employed. Short cavity lasers showed a high-frequency response compared to the original DFB lasers and achieved a short pulse width of 13 ps by standard gain-switched operation.     

Wavelength-tunable 40-GHz picosecond harmonically mode-locked fiber laser source

We demonstrate a novel 40-GHz mode-locked fiber laser that utilizes a single active device to provide both gain and mode-locking. The laser produces pulses as short as 2.2 ps, is tunable over a 27-nm band centered at 1553 nm, and exhibits long-term stability without cavity-length feedback control. The pulse train at 1556 nm was used in a 40-Gb/s transmission experiment over 45 km with a low 0.4-dB power penalty.     

105-GHz bandwidth metal-semiconductor-metal photodiode

The authors report the fabrication and characterization of a metal-semiconductor-metal (MSM) Schottky-barrier photodiode with a measured impulse response shorter than 5 ps and a bandwidth of 105 GHz at a bias voltage of 0.5 V. It is shown that the experimental results are in good agreement with numeric calculations. Because of its high performance and process compatibility with GaAs FETs, this type of photodiode is very well suited for monolithic micro- and millimeter-wave optoelectronic circuits     

1.5-GHz bandwidth light modulator

A simple light modulator employing an interdigital microwave circuit and a short electrooptic crystal is described. Greater than 30 percent amplitude modulation, obtained by modulating the crystal birefringence, has been obtained between 0.8 and 2.3 GHz using 5 watts of RF drive power.     

Polyimide-planarized vertical-cavity surface-emitting lasers with 17.0-GHz bandwidth

High-speed oxide-confined polyimide-planarized 850-nm vertical-cavity surface-emitting lasers exhibit -3-dB modulation bandwidths up to 17.0 GHz. The devices are fabricated using a reproducible, simple process incorporating polyimide with good adhesion that does not require implantation or semiinsulating substrates to achieve low capacitance.     

40-GHz mode-locked fiber-ring laser using a Mach-Zehnder interferometer with integrated SOAs

A 40-GHz mode-locked fiber-ring laser based on an optically controlled modulator is presented and analyzed in detail. The modulator is a monolithic InGaAsP-InP Mach-Zehnder interferometer with integrated semiconductor optical amplifiers, which allows optical pulse generation synchronized to an external optical clock pulse stream. The laser generates nearly transform-limited Gaussian pulses of 2.5-ps width and up to 9-mW mean output power with less than 130 fs of timing jitter, and it is wavelength tunable over more than 30 nm. The relationship between key laser parameters and the output pulse characteristics is analyzed experimentally and numerically. An improved cavity design permits the generation of shorter pulses of 1.0-ps width.     

SiGe differential transimpedance amplifier with 50-GHz bandwidth

InP and SiGe technologies are both attractive for design of circuits operating at 40 GB/s and beyond. In this paper, we describe a fully differential SiGe transimpedance amplifier (TIA) suitable for differential phase-shift keying applications. The TIA exhibits 49 dB-/spl Omega/ transimpedance, greater than 50-GHz bandwidth, and input-referred current noise less than 30 pA//spl radic/Hz. For comparison, we have also developed a similar TIA in an InP double-heterostructure bipolar transistor technology. The InP TIA had 48 dB-/spl Omega/ transimpedance and 49-GHz bandwidth.     

15-GHz modulation performance of integrated DFB laser diode EA modulator with identical multiple-quantum-well double-stack active layer

Monolithically integrated InGaAsP 1.55-/spl mu/m ridge waveguide distributed feedback laser diodes with an electroabsorption modulator using an identical active multiquantum-well (MQW) layer structure with two different QW types exhibit low-threshold currents <18 mA. The 3-dBe cutoff frequency of 200-/spl mu/m-long modulators exceeds 15 GHz. 10-Gb/s transmission experiments with a voltage swing of 1.0 V/sub pp/ demonstrate the potential of this novel integration scheme.     

Detailed investigation on reliability of wavelength-monitor-integrated fixed and tunable DFB laser diode modules

A highly reliable integration of a wavelength monitor (WM) in an industry standard 14-pin butterfly package has been successfully achieved by using soldering and YAG welding techniques. Mechanical integrity and endurance tests for fixed and tunable distributed-feedback (DFB) laser diode modules (LDMs) were performed according to an extended Telcordia GR-468-CORE in order to appreciate the fixtures of the WM part composed of a prism, a Fabry-Pe/spl acute/rot etalon, power, and WM photodiodes. Wavelength and a fiber output power were evaluated as a function of duration time for each test. Incident light angles change against an etalon and an optical coupling deviates due to the separation between a laser diode part and a WM part for tunable DFB LDMs. The two occurrences have a profound influence on wavelength drifts. It was found that the wavelength drifts were less than /spl plusmn/5 pm under mechanical and thermal stresses for both types of DFB LDMs. It was also confirmed that the coated and mounted etalon itself was also highly reliable under thermal stresses. These results show that the WM-integrated fixed and tunable DFB LDMs were fully applicable to next-generation dense-wavelength-division-multiplexing (DWDM) systems of 50- and 25-GHz channel spacing.     

30-GHz bandwidth 1.55-/spl mu/m strain-compensated InGaAlAs-InGaAsP MQW laser

High-speed 1.55 /spl mu/m laser diodes with a 3-dB modulation bandwidths of 30 GHz were fabricated by using short-cavity mushroom structures with undoped, strain-compensated InGaAlAs-InGaAsP twenty-quantum-well active regions. The bandwidths were achieved at low bias current of 100 mA. The laser exhibited a high differential gain of 1.54/spl times/10/sup -15/ cm/sup 2/ and a small K factor of 0.135 ns. These results were achieved by using an In/sub 0.386/Ga/sub 0.465/AlAs barrier with 0.83% tensile strain to reduce the thermal emission time of holes from wells and hence the hole transport time.     

A power efficient differential 20-GHz low noise amplifier with 5.3-GHz 3-dB bandwidth

A 20-GHz differential two-stage low-noise amplifier (LNA) is demonstrated in a foundry digital 130-nm CMOS technology with 8-metal layers. This LNA has 20-dB voltage gain and /spl sim/5.5-dB noise figure at 20GHz with 24-mW power consumption. The measured IP/sub 1 dB/ and IIP/sub 3/ are -11 dBm and -4dBm. Compared to the previously published bulk CMOS LNAs operating above 20GHz, this LNA has exceptionally low power and current consumption especially considering its differential topology and wide bandwidth.     

Modulator integrated DFB lasers with more than 600-km transmission capability at 2.5 Gb/s

The modulator integrated DFB laser diodes with more than 600-km transmission capability over normal fiber at 2.5 Gb/s, have been reproducibly achieved. The longest transmission length obtained in the experiment is as long as 800 km.