Coherent communication link using diode-pumped lasers

Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators

Prototype laser-diode-pumped solid state laser transmitters

Monolithic, diode-pumped Nd:YAG ring lasers can provide diffraction-limited, single-frequency, narrow-linewidth, tunable output which is adequate for use as a local oscillator in a coherent communication system. A laser was built which had a linewidth of about 2 kHz, a power of 5 milliwatts, and which was tunable over a range of 30 MHz in a few microseconds. This laser was phase-locked to a second, similar laser. This demonstrates that the powerful technique of heterodyne detection is possible with a diode-pumped laser used as the local oscillator. Laser diode pumping of monolithic Nd:YAG rings can lead to output powers of hundreds of milliwatts from a single laser. A laser was built with a single-mode output of 310 mW. Several lasers can be chained together to sum their power, while maintaining diffraction-limited, single frequency operation. This technique was demonstrated with two lasers, with a total output of 340 mW, and is expected to be practical for up to about ten lasers. Thus with lasers of 310 mW, output of up to 3 W is possible. The chaining technique, if properly engineered, results in redundancy. The technique of resonant external modulation and doubling is designed to efficiently convert the continuous wave, infrared output of our lasers into low duty-cycle pulsed green output. This technique was verified through both computer modeling and experimentation. Further work would be necessary to develop a deliverable system using this technique

Fertility preservation in pre-pubertal girls with cancer : the role of ovarian tissue cryopreservation

Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.With increasing numbers of survivors of cancer in young people future fertility and ovarian function are important considerations that should be discussed before treatment commences. Some young people, by nature of the treatment they will receive, are at high risk of premature ovarian insufficiency and infertility. For them, ovarian tissue cryopreservation (OTC) is one approach to fertility preservation that remains both invasive and for young patients experimental. There are important ethical and consent issues that need to be explored and accepted before OTC can be considered established in children with cancer. In this review we have discussed a framework for patient selection which has been shown to be effective in identifying those patients at high risk of premature ovarian insufficiency (POI) and who can be offered OTC safely.PostprintPeer reviewe

Live birth and maternity outcome in childhood and adolescent cancer survivors under 18 years at diagnosis: a 40-year population-based cohort study

Survival from childhood and adolescent cancer has increased, but the chance of a livebirth in female survivors under 18 years at diagnosis may be reduced

Non-growing follicle density is increased following adriamycin, bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy in the adult human ovary

Funded by UK Medical Research Council Grants G0901839 and MR/L00299X/1.Study question: Do the chemotherapeutic regimens of ABVD (adriamycin, bleomycin, vinblastine and dacarbazine) or OEPA-COPDAC (combined vincristine, etoposide, prednisone, doxorubicin (OEPA) and cyclophosphamide, vincristine, prednisone, dacarbazine (COPDAC)) used to treat Hodgkin lymphoma (HL), affect the density, morphology and in vitro developmental potential of human ovarian follicles? Summary answer: Ovarian tissue from women treated with ABVD contained a higher density of non-growing follicles (NGFs) per cubic millimetre and increased numbers of multiovular follicles but showed reduced in vitro growth compared with patients with lymphoma who had not received chemotherapy, patients treated with OEPA-COPDAC, age-matched healthy women and age-related model-predicted values. What is known already: Chemotherapy regimens can cause a loss of follicles within the ovary that depends on the drugs given. Early stage HL is commonly treated by ABVD, a non-alkylating regimen which apparently has ovarian sparing qualities, thus it is important to investigate the histological appearance and distribution of follicles within ABVD-treated ovarian tissue. Study design, size, duration: Thirteen ovarian biopsies were obtained from HL patients (6 adolescents and 7 adults) and one biopsy from a non-HL patient. Two HL patients and the non-HL patient had received no treatment prior to biopsy collection. The remaining 11 HL patients received one of two regimens; ABVD or OEPA-COPDAC. Tissue was analysed histologically and compared to biopsies from healthy women, and in a sub-group of patients, tissue was cultured for 6 days in vitro. Participants/materials, setting, methods: Ovarian biopsies were obtained from patients undergoing ovarian cryopreservation for fertility preservation, and from healthy women at the time of Caesarian section (‘obstetric tissue’). Follicle number and maturity were evaluated in sections of ovarian cortical tissue, and compared to an age-related model of mean follicle density and to age-matched contemporaneous biopsies. The developmental potential of follicles was investigated after 6 days tissue culture. Main results and the role of chance: A total of 6877 follicles was analysed. ABVD-treated tissue contained a higher density of non-growing follicles/mm3 (230±17) (mean±SEM) than untreated (110±54), OEPA-COPDAC-treated (50±27 and obstetric tissue (20±4)(P< 0.01),with follicle density 9-21 standard deviations higher than predicted by an age-related model. Bi-ovular and binucleated non-growing follicles occurred frequently in ABVD-treated and in adolescent untreated tissue but were not observed in OEPA-COPDAC-treated or obstetric tissue, although OEPA-COPDAC-treated tissue contained a high proportion of morphologically abnormal oocytes (52% versus 23% in untreated, 22% in ABVD-treated and 25% in obstetric tissue; P< 0.001). Activation of follicle growth in vitro occurred in all groups, but in ABVD-treated samples there was very limited development to the secondary stage, whilst in untreated samples from lymphoma patients growth was similar to that observed in obstetric tissue (untreated; P< 0.01 versus ABVD-treated, ns versus obstetric). Large scale data: N/A Limitations, reasons for caution: Although a large number of follicles were analysed, these data were derived from a small number of biopsies. The mechanisms underpinning these observations have yet to be determined and it is unclear how they relate to future fertility. Wider implications of the findings: This study confirms that the number of NGFs is not depleted following ABVD treatment, consistent with clinical data that female fertility is preserved. Our findings demonstrate that immature follicle density can increase as well as decrease following at least one chemotherapy treatment. This is the first report of morphological and follicle developmental similarities between ABVD-treated tissue and the immature human ovary. Further experiments will investigate the basis for the marked increase in follicle density in ABVD-treated tissue.PostprintPeer reviewe