Critical study of the vertical-cavity surface emitting laser electrical access for integrated optical sub-assembly

The proposal contribution aims at highlighting the consequence of the impedance mismatching in Vertical-Cavity Surface-Emitting laser (VCSEL)-based optical subassembly for optical interconnection applications. The integration of this micro laser diode needs a particular care to avoid electromagnetic coupling which could transform the advantage of the VCSEL technology in a weakness. Indeed, the vertical emission perpendicular to the active layer gives the possibility to achieve the need of planarization of the optoelectronic circuits and the design of VCSEL arrays. That is why it is of great interest to develop an optoelectronic model including the electrical access effect. This model is based on the VCSEL rate equation comparison with a behavioural small-signal equivalent circuit. Scattering parameters of various VCSEL structures and various VCSEL chip submounts are tested. This characterization allows the validation of the laser model and emphasizes the influence of the electrical access in the light transmission. In a particular VCSEL array structure, a crosstalk phenomenon is also observed. In other cases, the frequency rise involves modification of the laser frequency response. Consequently the electrical access of the VCSEL needs to be improved in order to avoid an inadequate utilization of the VCSEL

VCSEL intrinsic response extraction using T-Matrix formalism

We present a new method to remove the parasitics contribution to the VCSEL chip response, in order to obtain the intrinsic S21 behavior. The on-chip VCSEL is defined as two cascaded two-port subsystems representing the electrical access and the VCSEL optical cavity respectively. S11 and S21 parameters measurements are carried-out using a probe station to characterize the chip response. An electrical equivalent circuit defining the behavior of the electrical access is combined with T-Matrix formalism to remove the parasitics contribution from the measured S21 response. Results allow us to determine the intrinsic 3-dB bandwidth of the VCSEL

Dynamic properties of silicon-integrated short-wavelength hybrid-cavity VCSEL

We present a vertical-cavity surface-emitting laser (VCSEL) where a GaAs-based "half-VCSEL" is attached to a dielectric distributed Bragg reflector on silicon using ultra-thin divinylsiloxane-bis-benzocyclobutene (DVS-BCB) adhesive bonding, creating a hybrid cavity where the optical field extends over both the GaAs- and the Si-based parts of the cavity. A VCSEL with an oxide aperture diameter of 5 mu m and a threshold current of 0.4 mA provides 0.6 mW output power at 845 nm. The VCSEL exhibits a modulation bandwidth of 11 GHz and can transmit data up to 20 Gbps

Packaging technology enabling flexible optical interconnections

This paper reports on the latest trends and results on the integration of optical and opto-electronic devices and interconnections inside flexible carrier materials. Electrical circuits on flexible substrates are a very fast growing segment in electronics, but opto-electronics and optics should be able to follow these upcoming trends. This paper presents the back-thinning and packaging of single opto-electronic devices resulting in highly flexible and reliable packages. Optical waveguides and optical out-of-plane coupling structures are integrated inside the same layer stack, resulting in complete VCSEL-to-PD links with low total optical losses and high resistance to heat cycling and moisture exposure

1.3μm single-mode VCSEL-by-VCSEL optical injection-locking for enhanced microwave performance

Microwave performance of 1.3μm optically injection-locked single-mode VCSELs functioning at room temperature is presented. The experiment has been performed using two identical unpackaged VCSELs on two separate probe-stations. Three-fold increase in the 3-dB cut-off frequency of S21 spectra have been observed under VCSEL-by-VCSEL optical injection-locking

Embedded flexible optical shear sensor

Monitoring shear stresses is increasingly important in the medical sector, where the sensors need to be unobtrusive, compact and flexible. A very thin and flexible sensor foil is presented based on the shear stress dependent coupling change of optical power between a laser and photodiode chip that were separated by a deformable sensing layer. These opto-electronic components were embedded in a very thin foil of only 40 mu m thick. The sensitivity and measurement range can be modified by selecting the material properties of the sensing layer. The sensor response showed to be reproducible and the influence of normal pressure on the sensor was very limited

Vertical-cavity surface-emitting laser with a liquid crystal external cavity

We have developed a technology to integrate a thin layer of liquid crystal (LC) on top of a Vertical-Cavity Surface-Emitting Laser (VCSEL). Based on this technology, we demonstrate VCSELs with a chiral liquid crystal (CLC) layer, which acts as a tuneable mirror. The reflection properties of the CLC layer are controlled by temperature. Next we demonstrate VCSEL devices with tuneable external cavity using a nematic LC layer incorporated with an additional dielectric mirror (SiO2/Ta2O5). The VCSEL and the LC layer can be electrically driven independently and the optical length in the external cavity can be tuned by the applied voltage on the LC layer. In both configurations we show that the emission properties of the VCSEL can be changed, in terms of emission wavelength, polarization state and/or lasing threshold

Power and wavelength polarization bistability with very wide hysteresis cycles in a 1550nm-VCSEL subject to orthogonal optical injection

We have measured optical power and wavelength polarization bistability in a 1550nm-Vertical Cavity Surface-Emitting Laser (VCSEL) subject to orthogonally-polarized optical injection into the orthogonal polarization of the fundamental transverse mode. Optical bistability with very wide hysteresis cycles, up to four times wider than previously reported results has been measured for both the optical power and wavelength domain. We also report the experimental observation of three different shapes of polarization bistability, anticlockwise, clockwise and X-Shape bistability, all of them with wide hysteresis cycles. This rich variety of behaviour at the important wavelength of 1550 nm offers promise for the use of VCSELs for all-optical signal processing and optical switching/routing applications. ©2009 Optical Society of America