Simplified modeling of frequency behavior in photonic crystal vertical cavity surface emitting laser with tunnel injection quantum dot in active region

In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers（Ph C-TIQD-VCSEL） are studied through analyzing a modified modulation transfer function. The function is based on the rate equations describing the carrier dynamics at different energy levels of dot and injector well. Although the frequency modulation response component associated with carrier dynamics in wetting layer（WL） and at excited state（ES） levels of dots limits the total bandwidth in conventional QD-VCSEL, our study shows that it can be compensated for by electron tunneling from the injector well into the dot in TIQD structure. Carrier back tunneling time is one of the most important parameters, and by increment of that, the bias current dependence of the total bandwidth will be insignificant. It is proved that at high bias current, the limitation of the WL-ES level plays an important role in reducing the total bandwidth and results in rollovers on 3-d B bandwidth-I curves. In such a way, for smaller air hole diameter of photonic crystal, the effect of this reduction is stronger.

Establishing the lower limits of total serum testosterone among Chinese proven fertile men who received treatment of assisted reproductive technology

Testosterone(T)plays a crucial role in spermatogenesis because extremely low levels of intratesticular T lead to correspondingly low serum levels of total T(tT),severe disorders of spermatogenesis,and male sterility.However,there is little consensus on the lower limits of serum tT in proven fertile men undergoing assisted reproductive technology treatments in Chinese or other Asian populations.We aimed to establish the reference range of serum tT based on a population of 868 fertile Chinese men undergoing in vitro fertilization or intracytoplasmic sperm injection and embryo transfer(IVF/ICSI-ET)treatments.We defined a fertile man as having had a live baby with his partner as recorded in our IVF registration system.The lower limits of serum tT were established using a Siemens IMMULITE 2000 chemiluminescent system.The 1st,2.5th,and 5th percentiles and their 95%confidence intervals(CIs)were 3.6(95%CI:2.7–4.1)nmol l−1,4.3(95%CI:4.1–5.0)nmol l−1,and 5.6(95%CI:4.8–5.8)nmol l−1,respectively.Using the linear correlation of serum tT between the Siemens platform and a liquid chromatography–tandem mass spectrometry platform,the calculated lower limits of serum tT were also established for fertile Chinese men undergoing IVF/ICSI-ET treatments,which will benefit the clinical diagnosis and treatment of male infertility during such procedures.