InP Laser Diode Research Articles

Gain Coefficient Comparison between Silicon and InP Laser Diode Substrate

The article presents the study on the comparison of gain coefficient of laser diode on silicon and InP substrate. Fabry–Perot GaInAsP bulk laser diode on InP/Si substrate is successfully obtained to study the optical gain coefficient of laser diode. The influences of temperature, threshold current comparison, and optical gain achievements between bulk InP/Si laser diode substrate and InP laser diode substrate are also analyzed using the same growth structure. A new approach is found by the research group which involves bonding of 1 μm InP semiconductor crystal and a low‐cost silicon crystal prior to epitaxial laser structure growth. With the help of metal–organic vapor‐phase epitaxy technique, GaInAsP double‐heterostructure laser is epitaxially deposited on the well‐bonded InP/Si crystal. Fabry–Perot lasing under pulsed condition is achieved, and the lasing characteristics of InP/Si substrate are compared with that of InP laser device to study the gain coefficient.

Multi-100 GbE and 400 GbE Interfaces for Intra-Data Center Networks Based on Arrayed Transceivers With Serial 100 Gb/s Operation

We demonstrate a 2 × 100 Gb/s transmitter and a 4 × 100 Gb/s receiver as the key components for multi-100-GbE and 400-GbE optical interfaces in future intradata center networks. Compared to other approaches, the two devices can provide significant advantages in terms of number of components, simplicity, footprint, and cost, as they are capable of serial operation with nonreturn-to-zero on-off keying format directly at 100 Gb/s. The transmitter is based on the monolithic integration of a multimode interference coupler with two Mach-Zehnder modulators on an electro-optic polymer chip, and the hybrid integration of this chip with an InP laser diode and two multiplexing and driving circuits. The receiver on the other hand is based on the hybrid integration of a quad array of InP photodiodes with two demultiplexing circuits. Combining the two devices, we evaluate their transmission performance over standard single-mode fibers without dispersion compensation and achieve a BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> after 1000 m and a BER below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> after 1625 m at 2 × 80 Gb/s, as well as a BER below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> after 1000 m at 2 × 100 Gb/s. Future plans including the development of tunable 100 GbE interfaces for optical circuit-switched domains inside data center networks are also discussed.

FIB-induced electro-optical alterations in a DFB InP laser diode

A recent experiment used FIB to induce local modification in a single-mode edge emitting laser operating at 1310nm, and led to a method for estimating gain parameters. In this experiment, the final FIB modification introduced large variation in electrical characteristics that were not analysed in detail, and even seemed to contradict the basic laser model that the experiment itself aimed to confirm. This paper focuses on this puzzling point, and solves it with a circuital hypothesis, a circuit simulation and a direct inspection by XEBIC.

Serial 100 Gb/s connectivity based on polymer photonics and InP-DHBT electronics

We demonstrate the first integrated transmitter for serial 100 Gb/s NRZ-OOK modulation in datacom and telecom applications. The transmitter relies on the use of an electro-optic polymer modulator and the hybrid integration of an InP laser diode and InP-DHBT electronics with the polymer board. Evaluation is made at 80 and 100 Gb/s through eye-diagrams and BER measurements using a receiver module that integrates a pin-photodiode and an electrical 1:2 demultiplexer. Error-free performance is confirmed both at 80 and 100 Gb/s revealing the viability of the approach and the potential of the technology.

Transient wavelength performance of 153 μm InP laser diodes for pumping of Er^3+-doped solid-state lasers

The transient wavelength performance of high-power InP laser diode stacks with internal Bragg gratings is studied experimentally. Because of the wavelength selective nature of the internal grating, which is decoupled from the actual gain profile dynamics of the laser diode, the wavelength drift with respect to temperature and current is greatly reduced and steady-state conditions are reached after a short settling time of less than 50 ms.

Singlemode emission at 2 [micro sign]m wavelength with InP based quantum dash DFB lasers

Long wavelength distributed feedback (DFB) laser diodes based on InP quantum dash-in-a-well material have been fabricated and investigated at room temperature under continuous-wave operation. Singlemode emission of InP laser diodes at wavelengths above 2 µm is demonstrated for the first time.

High-Temperature and High-Frequency Operation of 1.3 μm AlGaInAs ∕ InP Laser Diodes Using Silicon Oxide Planarization

In this article, a self-terminated oxide polish (STOP) planarization technique is utilized to fabricate high-temperature and high-speed ridge-waveguide laser diodes (LDs). The as-cleaved LDs fabricated by this STOP technique exhibit a threshold current of 8.5 and , and a light output power of 27 and at for 0 and , respectively. The characteristic temperature is from 0 to and from 80 to . The full width at half maximum of the lateral far-field angle is for the conventional ridge LDs and reduces to for the LDs by the STOP technique. The modulation bandwidth at of the LDs can reach 16.9 at and at .

The joint strength and microstructure of fluxless Au/Sn solders in InP-based laser diode packages

The joint strength and microstructure of fluxless Au/Sn solders in InP-based laser-diode packages after thermal-aging testing were studied experimentally and numerically. Specimens were aged at 150°C for up to 64 days. The joint strength decreased as aging time increased. The microstructure and fracture surface of the Au/Sn solder joints showed that the joint strength decrease was caused by both the enlargement of the initial voids and an increase in the number of voids as the aging time increased. Finite-element method (FEM) simulations of joint strength were in good agreement with experimental measurements. Both experimental and numerical results indicate that the enlargement of the initial voids and an increase in the number of voids, caused by stress concentration as the aging period increased, resulted in the weakness of joint strength. The effect of temperature-cycling testing on the power variation of the InP laser diodes using fluxless Au/Sn solders was also studied. It was shown that the laser diodes operated in the stable condition up to 500 cycles.

Passive modelocking of InGaAsP∕InP laser diode over wide operating temperature range

The passive modelocked operation of an InGaAsP/InP laser diode, with a novel design of adaptable saturable absorber, up to an operating temperature of 75°C, is reported. To the authors' best knowledge, this is the first demonstration of high-temperature operation of a passively modelocked laser diode. The effect of the operating temperature on the operating frequency and the tuning range is described.

Heat transfer and residual stress modeling of a diamond film heat sink for high power laser diodes

A three-dimensional finite element model of heat transfer and residual stress within high power laser diodes and their heat sinks is developed. These components are typically used in telecommunication applications. The model addresses both p-side down and p-side up laser diodes mounted on a variety of commercially available gold plated diamond heat sinks. In addition, the model is optimized with respect to the dimensions of the diamond film, and the laser diode cavity lengths. Finally, the design and performance of diamond film heat sinks for high performance GaAs and InP laser diodes are discussed. The results demonstrate the superior performance achieved through thermal engineering of the dominant thermal transport path from the laser diode heat source through diamond films to the heat sink.

Hybrid microlaser encoder

We have developed a microlaser encoder that can detect displacements relative to an external grating scale with a resolution on the order of 10 nm. Its size is only a few tens of a percent of a conventional encoder's. A long-lasting InP laser diode with a wavelength of 1550 nm was bonded, along with several photodiode chips, within an alignment accuracy of 1 /spl mu/m onto a silicon planar lightwave circuit chip. The chip is 2.3 mm /spl times/ 1.7 mm and includes a fluorinated polyimide lightwaveguide fabricated in advance. A wide gap of more than 600 /spl mu/m was obtained between the external grating scale and the encoder despite the tiny size of the sensor. When used as a rotary encoder, the number of rotations could also be detected. Thus, this microencoder satisfies the market requirements for practical use.

GaAsInP heteroepitaxy and GaAsInP MESFET fabrication by MOVPE

Lattice-mismatched heteroepitaxy has attracted considerable attention in recent years. A great interest of these systems is the possibility of integrating devices from different materials on a single substrate. 1.3 and 1.5 μm InGaAs(P)/InP laser diodes are essential for optical communication, whereas InP field effect transistor technology is less developed than that of GaAs MESFET. The performances of laser diodes are much more sensitive to a high density of dislocations, so it would be interesting to grow GaAs MESFET on InP for integration with 1.3 and 1.5 μm lasers. Due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP, it is very difficult to grow GaAs epilayers of high quality on it is very difficult to grow of GaAs epilayer high quality on InP substrates due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP. A new method, metalorganic source modulation epitaxy (MOSME), which improves the crystal quality of GaAs epilayers on InP substrates by MOVPE, has been adopted in our laboratory. The lowest full width at half maximum (FWHM) of the double crystal X-ray (DCX) diffraction spectra reaches as low as 120 arcsec for a 5 μm thick layer. Structural properties (misorientation, lattice parameters and crystal quality) of 1.0-5.0 μm thick GaAs layers grown on InP have been measured by DCX diffraction. On GaAs MESFETs grown on InP, we have measured g m = 100 ms/mm.For these transitions, the current gain cut-off frequency (F t ) is around 12 GHz and the maximum frequency of oscillation (F max ) is higher than 30 GHz.

Bonding of InP laser diodes by Au-Sn solder and tungsten-based barrier metallization schemes

Ti/W/Au-Sn and Ti/WxMy/Au-Sn schemes were studied as alternative metallization schemes to the traditionally used Ti/Pt/Au-Sn system for the bonding of InP laser diodes to heatsinks, and in particular to CVD diamond parts. The study comprised the Ti/W, Ti/W1(Au-Sn) and Ti/W1(Ni-Sn) barrier metal schemes, co-deposited in between the Au-Sn solder and the submount. In particular, reactivity and thermodynamic stability of the systems, acid the integrity of the barrier metal to the AuSn solder interface through the thermal bonding refreezing and reflow cycles were tracked. Premature freezing of the solder through the bonding cycles was attributed to the intermixing of the underlying barrier metal and the solder, suggesting an insufficient thermodynamic stability. Dewetting of the solder from the barrier metals through the reflowing cycle, subsequent to the completion of the bonding cycle, occurs due to the excellent inert nature of the solder to the barrier system, but exhibited the deficiency of poor solder to barrier metal adhesion. The TIM, system performed as an absolute inert barrier under the Au-Sn solder, in which no premature freezing phenomena were observed through the bonding cycle, resulting, however, in a delamination of the solder from the Ti/W, while reflown both under flux and forming-gas. In order to maintain the stable nature of this system, but to improve the barrier-solder interfacial integrity, W-Au, W-AuSn and W-NiSn co-deposited intermediate adhesion layers were introduced in between the W layer and the Au-Sn solder. As a result, the adhesion of the solder to the barrier metal improved, while the most stable performance was observed while applying the W/W(NiSn) barrier system under the Au-Sn solder. The first local freezing phenomenon of the bonding solder, while using this system, was observed only after heating the sample to 320 degrees C for more than 3 min and more than 1 h was needed to completely freeze the entire solder. in addition, an excellent solder to metal interfacial integrity was observed through the gas and flux reflow cycle. Thus, the W/W(NiSn) barrier metallization is recommended as a superior scheme to replace the traditionally used Ti/Pi system for bonding laser diodes to any type of submount using Au-Sn solder.

Metallization Systems for Bonding of InP Laser Diodes to CVD-Diamond Submounts

ABSTRACTSome metallization systems consisting of barrier metals and Au-Sn (multiple alternating layers) were studied as a bonding schemes of InP-based laser diodes to the first time used, CVD-diamond submounts. The first system to be studied, which was traditionally used in various other applications was Ti(100nm)/Pt(200nm)/Au(500nm)/Au-Sn(2.5 μm). This structure provided a molten Au-Sn layer of eutectic composition (80:20 wt%) on top of the Ti/Pt metals for about 6 sec, while heated at temperatures of 300 to 350°C, and allowed for efficient bonding of the device to the submount. Longer heating durations, however, led to reaction between Pt and Sn to consume significant amounts of Sn from the solder, thus elevating its melting temperature and resolidifying the solder. With optimum bonding conditions, a high quality bond of the InP-based laser diode to the CVD-diamond submount was observed, and a superior electrical performance of the diode was measured compared to diodes that were bonded with the standard In/BeO configurations. In order to maintain the superior performance of the InP laser diode bonded assembly but improve the thermodynamic stability of the metallurgical system and thus extending the bonding processing window, various metals such as W and Cr were studied as a replacement for the Ti/Pt barrier metals in between the CVD-diamond submount and the Au-Sn solder. While applying the W layer, a thin Ti(10nm) layer was introduced in between it and the Au-Sn to improve the solder wettability. The W layer was found to remain intact after heating at 350°C for durations as long as 5 min, and thus, due to the inert nature of the Au-Sn/W interface, the Au-Sn ratio was kept uniform at the eutectic liquid composition through a long heating duration (up to 5 min). Minimum reaction was observed, as well, at the Au-Sn/Cr interface, while executing a Ti(100nm)/Cr(200nm)/Au-Sn(1.5 μm) system, and thus allowed for an excellent bonding of the InP laser diodes to the CVD-diamond submounts.

InP LD with PD fabricated by Br2–reactive—ion–etching technique

AbstractIt is important to monitor the optical output of a laser diode (LD) in an opto‐electric integrated circuit (OEIC). Therefore, in monolithic fabrication of an LD with a photodetector (PD), chlorine (Cl)‐based gas has been used to carry out dry etching for forming a laser facet in InP‐based materials. However, in this technique, selectivity of etching is not sufficient. In our study, Br2 was employed as the etching gas using Ti for the etching mask. Our technique can provide a selectivity of etching as high as 34 and has been found to be effective in forming a laser facet.Using reactive ion etching (RIE) with Br2 gas, a laser facet was formed in a buried heterostructure laser diode (BHLD) with a PD. The threshold current and optical output of the LD were 35 ‐ 50 mA and 5 ‐ 10 mW, respectively, while the sensitivity of the PD was 0.49 A/W. The isolation resistance between the LD and PD was 1 Mω.The result of this study indicates that our technique will be effective in high‐density integration of OEICs.

On spot sizes of 1.3 ‐1.55‐μm InGaAsP/InP semiconductor laser diodes

AbstractThe spot sizes for the fundamental TE modes of InGaAsP / InP laser diodes in directions parallel and perpendicular to the junction plane have been investigated based on the effective refractive index approach. The analytical results are in good agreement with the reported measured values in the literature. The results can be used to calculate the coupling efficiency between laser diodes and single‐mode fibers.

Evidence for Auger and free-carrier losses in GaInAsP/InP lasers: Spectroscopy of a short wavelength emission

We report the observation of two high-energy emission bands near 1.31 eV in Ga0.29In0.71As0.61P0.39 /InP laser diodes. One emission band is associated with recombination in the InP due to carrier leakage from the active layer. A second, more important emission band with an energy close to E0+Δ0 is associated with recombination of holes in the split-off valence band and electrons in the conduction band. The split-off valence band is significantly populated by Auger recombination and intervalence band absorption. From the dependence of the integrated E0+Δ0 luminescence intensity on injection current (below threshold) we determine an Auger coefficient for holes of C≂5×10−29 cm6 s−1 at T=300 K.