Frank H. Peters

Large-scale photonic integrated circuits

We present an overview of Infineras current generation of 100 Gb/s transmitter and receiver PICs as well as results from the next-generation 500 Gb/s PM-QPSK PICs.

Enhanced performance of offset-gain high-barrier vertical-cavity surface-emitting lasers

The temperature dependence and power output of vertical-cavity surface-emitting lasers (VCSELs) are addressed. The peak wavelength of the quantum well has been offset from the wavelength of the device cavity mode so that they are aligned at elevated temperatures. The result of this design change is to produce an 8- mu m-diameter VCSEL capable of operation to 145 degrees C, as well as CW operation of broad-area (70- mu m diameter) heat-sunk devices to record power levels. Fiber coupling experiments were also carried out, and a record 33-mW CW power was coupled to a multimode fiber. >

Band-gap engineered digital alloy interfaces for lower resistance vertical-cavity surface-emitting lasers

We report on a technique of grading the heterobarrier interfaces of a p‐type distributed Bragg reflector mirror to reduce the operating voltages of vertical‐cavity surface‐emitting lasers (VCSELs). We report VCSELs with lower operating voltages (2–3 V) and record continuous‐wave room‐temperature power‐conversion efficiencies (17.3%). We experimentally demonstrate that by using a parabolic grading and modulating the doping correctly, a flat valence band is generated that provides low voltage hole transport. The low resistance mirrors are achieved using low Be doping, digital‐alloy grading and 600 °C growth temperatures.

High efficiency submilliamp vertical cavity lasers with intracavity contacts

Contacts have been made to p- and n-type layers on opposite sides of the active region within the cavity of an InGaAs vertical cavity surface emitting laser. The two concentric ring contacts allow all electrical connections on and emission from the top surface of a semi-insulating GaAs substrate. The design includes a novel current leveling layer to minimize current crowding effects. A high external quantum efficiency of 46% has been measured with maximum output powers up to 6 mW for a 15 /spl mu/m diameter device and threshold currents of 0.72 mA for a 7 /spl mu/m diameter laser.<<ETX>>

17.3% peak wall plug efficiency vertical-cavity surface-emitting lasers using lower barrier mirrors

Modifications to the epitaxial growth of vertical-cavity surface-emitting laser (VCSEL) material have recently led to improved characteristics. By offsetting the quantum-well gain peak from the cavity mode, and implementing lower barrier p-type Al/sub 0.67/Ga/sub 0.33/As/GaAs DBR mirrors with parabolic interface gradings, better high-temperature operation and lower voltages have been achieved. These effects combine to yield a peak wall plug efficiency of 17.3% for room temperature, CW operation.<<ETX>>

Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration

A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 mum laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.

HIGH MODULATION EFFICIENCY OF INTRACAVITY CONTACTED VERTICAL CAVITY LASERS

A very high current modulation efficiency of 5.7 GHz/√(mA) has been demonstrated in a low threshold (0.85 mA) InGaAs vertical‐cavity surface‐emitting laser. These top surface emission devices have been fabricated with intracavity contacts on semi‐insulating substrates to realize their high speed potential. Data is presented for various laser diameters. Modulation bandwidths up to 9.3 GHz at a bias of only 4.5 mA have been measured for 7 μm diameter lasers. Derived parameters indicate that considerably higher bandwidths should be possible with better heat dissipation and modified cavity designs.

High-power temperature-insensitive gain-offset InGaAs/GaAs vertical-cavity surface-emitting lasers

The authors have grown 997 nm vertical-cavity surface-emitting lasers with an offset between the wavelength of the cavity mode and the quantum well gain peak to improve high temperature operation, and with higher aluminum-content barriers around the active region to improve the carrier confinement. They fabricated lasers of 8-15 and 20- mu m diameters. The 8- mu m-diameter devices exhibited CW operation up to 140 degrees C with little change in threshold current from 15 degrees C to 100 degrees C, and the 20- mu m-diameter devices showed CW output power of 11 mW at 25 degrees C without significant heat sinking.<<ETX>>

Practical Design of Lensed Fibers for Semiconductor Laser Packaging Using Laser Welding Technique

We propose a set of guidelines for the practical design of lensed fiber for the optical coupling of semiconductor lasers in butterfly packages using laser welding. These guidelines have optimized the tradeoff between coupling efficiency and alignment tolerance. Moreover, a radius of curvature of 11 mum is shown to be optimal for semiconductor lasers whose divergence angles range from 5deg to 30deg. To experimentally evaluate the design, lensed fibers were assembled by a Nd:YAG laser welding technique in conventional butterfly packages and their coupling efficiencies were 28%-72% without horizontal misalignment compensation.

High-speed high-temperature operation of vertical-cavity surface-emitting lasers

Vertical-cavity surface-emitting lasers emitting at 850 nm have been developed that are capable of 10-Gb/s operation at high temperatures. Measurements are made at 10 and 12.5 Gb/s at temperatures up to 150/spl deg/C.