Microfluidic tuning of distributed feedback quantum cascade lasers

Abstract:The design of highly wavelength tunable semiconductor laser structures is presented. The system is based on a one dimensional photonic crystal cavity consisting of two patterned, doubly-clamped nanobeams, otherwise known as a "zipper" cavity. Zipper cavities are highly dispersive with respect to the gap between nanobeams in which extremely strong radiation pressure forces exist. Schemes for controlling the zipper cavity wavelength both optically and electrically are presented. Tuning ranges as high as 75 nm are achieved for a nominal design wavelength of λ = 1.3 µm. Sensitivity of the mechanically compliant laser structure to thermal noise is considered, and it is found that dynamic back-action of radiation pressure in the form of an optical or electrical spring can be used to stabilize the laser frequency. Fabrication of zipper cavity laser structures in GaAs material with embedded self-assembled InAs quantum dots is presented, along with measurements of photoluminescence spectroscopy of the zipper cavity modes.

Section: Introductionmentioning

confidence: 99%

Optomechanical zipper cavity lasers: theoretical analysis of tuning range and stability

Alegre¹,

Perahia²,

Painter³

2010

“…In Ref. [21], filling the grooves of a DFB QC laser with a material or liquid whose refractive index can be easily modified allowed fine tuning of the laser operating frequency. All the aforementioned approaches exploit the real part of the material/liquid refractive index in order to induce a wavelength change.…”

Section: Introductionmentioning

confidence: 99%

Proof-of-principle of surface detection with air-guided quantum cascade lasers

Moreau¹,

Colombelli²,

Perahia³

et al. 2008

Abstract:We report a proof-of-principle of surface detection with air-guided quantum cascade lasers. Laser ridges were designed to exhibit an evanescent electromagnetic field on their top surface that can interact with material or liquids deposited on the device. We employ photoresist and common solvents to provide a demonstration of the sensor setup. We observed spectral as well as threshold currents changes as a function of the deposited material absorption curve. A simple model, supplemented by 2D numerical finite element method simulations, allows one to explain and correctly predict the experimental results.

“…The possibility of performing intra-cavity spectroscopy or sensing [9,10,11,12,13,14,15,16,17] with quantum cascade lasers is an alternative intriguing approach [18,19,20,21]. In such a scheme, the laser would react to a material (gas, fluid, or solid particles) deposited within or on the surface of the laser by detuning its emission wavelength or increasing its threshold current density.…”

Section: Introductionmentioning

confidence: 99%

“…There are a variety of laser cavity geometries that are amenable to such intra-cavity sensing. These include porous photonic crystal laser structures [9,10,11,15,22], edge-sensitive microdisk and microring lasers [19], or top-surface-sensitive devices in which the optical mode leaks above the semiconductor surface [21,23,24]. While the former approach involving photonic crystals can theoretically provide the highest sensitivity, since the intra-cavity region is accessible through the photonic-crystal holes, these structures also are more difficult to fabricate.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of air-guided quantum cascade lasers without top claddings

Moreau¹,

Bahriz²,

Colombelli³

et al. 2007

We report on quantum cascade lasers employing waveguides based on a predominant air confinement mechanism in which the active region is located immediately at the device top surface. The lasers employ ridge-waveguide resonators with narrow lateral electrical contacts only, with a large, central top region not covered by metallization layers. Devices based on this principle have been reported in the past; however, they employed a thick, doped top-cladding layer in order to allow for uniform current injection. We find that the in-plane conductivity of the active region -when the material used is of high quality -provides adequate electrical injection. As a consequence, the devices demonstrated in this work are thinner, and most importantly they can simultaneously support air-guided and surface-plasmon waveguide modes. When the lateral contacts are narrow, the optical mode is mostly located below the air-semiconductor interface. The mode is predominantly air-guided and it leaks from the top surface into the surrounding environment, suggesting that these lasers could be employed for surface-sensing applications. These laser modes are found to operate up to room temperature under pulsed injection, with an emission spectrum centered around λ ≈ 7.66 µm. Roberts, "Room temperature operation of λ ≈ 7.5 µm surface-plasmon quantum cascade lasers," Appl. Phys.