On-chip gain switched frequency comb generation using a two sectioned single cavity laser without additional optical injection.

A tunable comb source is demonstrated on a monolithically integrated photonic integrated circuit (PIC). The PIC is a two section device designed to produce a single mode tunable spectrum, and the comb is generated by gain switching one section of the two sectioned laser. The laser produces a single mode spectra with a tunable range of 1543 - 1565 nm, and combs were generated with a frequency range of 1 - 10 GHz without requiring additional optical injection to maintain the phase coherence.

Tunable, coherent optical comb source via on-chip bidirectional coupling.

A tunable comb source is demonstrated through gain switching on a three-sectioned photonic integrated circuit (PIC). The PIC consists of two mutually coupled lasers connected by a passive waveguide. One of these is a tunable, two-section, single mode laser.

Study on the proximity of QWI in InP-based AlGaInAs MQWs using the IFVD method and its application in single frequency teardrop laser diodes.

This paper presents our research on quantum well intermixing (QWI) of InP-based AlGaInAs/AlGaInAs multi-quantum wells using impurity-free vacancy-disordering (IFVD) and the QWI mask proximity effect and its application in the design and fabrication of a teardrop laser. Using a SiN film deposited by plasma-enhanced chemical vapor deposition (PECVD) as a QWI promoter mask and annealing under 700°C for 2 minutes, a 70 nm wavelength blue shift of a FP laser is achieved using InP-based AlGaInAs quantum well laser material. It is found that a 5 µm separation is needed between the QWI mask edges and the non-QWI area during the QWI process.

Universal generation of devil's staircases near Hopf bifurcations via modulated forcing of nonlinear systems.

The discrete circle map is the archetypical example of a driven periodic system, showing a complex resonance structure under a change of the forcing frequency known as the devil's staircase. Adler's equation can be seen as the direct continuous equivalent of the circle map, describing locking effects in periodic systems with continuous forcing. This type of locking produces a single fundamental resonance tongue without higher-order resonances, and a devil's staircase is not observed.

Integrated dual optical frequency comb source.

A monolithically integrated dual-channel optical frequency comb source is demonstrated in this paper. Three lasers are integrated on a single chip using a regrowth-free fabrication process in a master-slave-slave configuration. The master laser's power is split equally using a 1x2 multimode interference coupler and injection locks the two slave lasers.

Dynamics of on-chip asymmetrically coupled semiconductor lasers.

We investigate the dynamics of asymmetrically coupled semiconductor lasers on photonic integrated circuits in experiment and theory. The experimental observations are explained using a rate-equation model for coupled lasers incorporating a saturable coupling waveguide. We perform a bifurcation analysis of the coupled laser dynamics, focusing on the effects of the coupling phase and the dynamical difference between passive and saturable coupling waveguides.

Harmonic frequency locking and tuning of comb frequency spacing through optical injection.

We show, both experimentally and theoretically, that a slave laser injected with an optical frequency comb can undergo two distinct locking mechanisms, both of which decrease the output optical comb's frequency spacing. We report that, for certain detuning and relative injection strengths, slave laser relaxation oscillations can become undamped and lock to rational frequencies of the optical comb spacing, creating extra comb tones by nonlinear dynamics of the injected laser. We also study the frequency locking of the slave laser at detunings in between the injected comb lines, which add the slave laser's frequency to the comb.

Off-Axis Cavity-Enhanced Absorption Spectroscopy of NH in Air Using a Gain-Switched Frequency Comb at 1.514 μm.

A custom-designed gain-switched frequency comb (GSFC) source was passively coupled to a medium finesse ( ≈ 522) cavity in off-axis configuration for the detection of ammonia (NH) in static dry air. The absorption of ammonia was detected in the near infrared spectral region between 6604 and 6607 cm using a Fourier transform detection scheme. More than 30 lines of the GSFC output (free spectral range 2.

Data transmission at 1300 nm using optical interposer comprising hybrid integrated silicon waveguide and dilute nitride electroabsorption modulator.

High speed back-to-back transmission of NRZ data at 12.5 Gbit/s was achieved over a repeaterless optical network without the use of forward error correction or optical clock recovery using a hybrid integrated silicon photonics optical interconnect. The interconnect comprises an electroabsorption modulator based on dilute nitride multiple quantum well material on GaAs substrate optically coupled to large core silicon waveguide using passive alignment and flip-chip bonding.

Dynamics of two identical mutually delay-coupled semiconductor lasers in photonic integrated circuits.

We theoretically investigate a system of two mutually delay-coupled semiconductor lasers, in a face to face configuration for integration in a photonic integrated circuit. This system is described by single-mode rate equations, which are a system of delay differential equations with one fixed delay. Several bifurcation scenarios involving multistabilities are presented, followed by a comprehensive frequency analysis of the symmetric and symmetry-broken, one-color and two-color states.

Modeling mutually coupled non-identical semiconductor lasers on photonic integrated circuits.

We model the situation of two lasers in a face-to-face arrangement, optically coupled through an attenuating element, where the distance between the lasers is on a scale typical in photonic integration (hundreds of micrometers to millimeters). We account for the existence of a frequency difference between the two single-mode lasers. Modified versions of the Lang-Kobayashi equations were employed to describe the interaction.

Regrowth-free integration of injection locked slotted laser with an electroabsorption modulator.

Optical injection locking was used to red shift an integrated semiconductor laser up to 30 nm away from the main free running lasing mode. This injection locking of the laser beyond its band edge enabled its integration with an electroabsorption modulator to produce a 2.5 Gb/s eye diagram.

Analysis of multimode interferometers.

A general analytical formula describing the transfer function between the input and output of an arbitrary rectangular multimode interference (MMI) coupler has been derived using the elliptic theta function ϑ(x', z'). This formula provides the positions, amplitudes and relative phases of all the self-images of a given source. It is shown how the transfer function can be used as a propagation matrix for any rectangular NxM MMI.

Three-coherent-output narrow-linewidth and tunable single frequency 1x2 multi-mode-interferometer laser diode.

A 1x2 multi-mode-interferometer (MMI) laser diode was successfully designed and fabricated, which demonstrated three coherent outputs of tunable single frequency emission with more than 30dB side mode suppression ratio (SMSR), a tuning range of 25nm in C and L band, as well as 750 kHz linewidth. This 1x2 MMI laser could be expanded to more advanced configurations such as 1xN or MxN (M≥1, N>2) MMI lasers to achieve a multiple coherent output source. In addition, these lasers do not require material regrowth and high resolution gratings which can significantly increase the yield and reduce the cost.

Ge/Si heterojunction photodiodes fabricated by low temperature wafer bonding.

We report on the photoresponse of an asymmetrically doped p(-)-Ge/n(+)-Si heterojunction photodiode fabricated by wafer bonding. Responsivities in excess of 1 A/W at 1.55 μm are measured with a 5.

Investigation of active filter using injection-locked slotted Fabry-Perot semiconductor laser.

We investigate the selective amplification and filtering of injection-locked slotted Fabry-Perot semiconductor lasers. Current and temperature tuning are used to selectively filter and amplify subcarriers of coherent optical combs with a selectivity of at least 10 GHz with an optical gain of up to 18 dB for filtered lines. A side mode suppression ratio in excess of 20 dB is also achieved.

Optimal laser welding assembly sequences for butterfly laser module packages.

We present an optimal laser welding assembly sequence for butterfly laser packages: 1) initial shift, 2) front welding, 3) rear welding, 4) joint gripper releasing, 5) mechanical fine tuning of horizontal misalignment. This sequence has been optimized significantly by modeling the initial shift and experimental investigations of three assembly sequences. Our results show that misalignment from the Post-Weld-Shift (PWS) can be compensated by accurately estimating the initial shift in the vertical direction.