**6. References**


**5** 

*USA* 

**Mid-Infrared Surface-Emitting Two Dimensional** 

The mid-infrared (mid-IR) region, covering the electromagnetic spectrum from about 2.5 to 25 μm wavelength, is of unique interest for many applications, especially for molecular spectroscopy, because the vibrational frequencies of almost all target molecules and hydrocarbons are in this spectral region, such as NO, NO2, CO, CO2, HF, and CH4. The specific application areas for molecular spectroscopy include scientific research, vehicle exhaust investigation, atmospheric pollution monitoring, medical diagnostics and biological & chemical weapon detection. Besides molecular spectroscopy applications, there are also some other potential applications, such as free space optical communications, etc. (Tittel,

For all these applications, typical requirements for mid-IR lasers are manifold. First of all, to reach high spectral selectivity performance, a narrow spectral linewidth is needed. Secondly, optical output power should be larger than 100 μW to lift detector noise limits. (Tacke M. , 2001) Thirdly, high beam quality is favorable for optimum coupling with the gas sampling cell. Also, room temperature or thermoelectric-cooled operation is desirable, considering the additional weight, volumes and costs with the additional cryogenic cooling equipment. Furthermore, a compact set-up is preferable for hand-held *in situ* measurement

Two dimensional (2D) photonic crystal lasers, potentially have great practical applications in the mid-IR region due to their unique features in, for example, surface emission, circular beams, low threshold operation, miniaturization and simplicity of on-chip monolithic integration, etc. The studies of surface emitting 2D photonic crystal lasers started in and have expanded worldwide since the middle of the 1990s. The first 2D photonic crystal semiconductor laser of 1.55 μm emission peak was demonstrated in 1999. (Painter, et al., 1999) After that, this type of semiconductor lasers has been developed rapidly in near IR region. (Park, Hwang, Huh, Ryu, & Lee, 2001; Loncar, Yoshie, Scherer, Gogna, & Qiu, 2002; Altug, Englund, & Vuckovic, 2006) Unfortunately, mainly restricted by the etch-induced surface recombination, the research development of 2D photonic crystal semiconductor lasers in mid-IR range of electromagnetic spectrum was relatively slow. Even so, due to their intrinsic advantages addressed previously, this type of lasers operating in mid-IR range is

**1. Introduction** 

Richter, & Fried, 2003)

in the field.

**Photonic Crystal Semiconductor Lasers** 

Binbin Weng and Zhisheng Shi

*School of Electrical and Computer Engineering University of Oklahoma, Norman Oklahoma* 

Zhang H. Y. ; Zhang Y. P. ; Wang P. et al. (2007). *Frequency response in photonic heterostructures consisting of single-negative materials*. Journal of Applied Physics, Vol. 101, No. 1, pp. 013111, 2007
